The only thing I can say is there are geniune reasons the top cafes in the US and the world use La Marzocco machines.
Positive Product Points
Dual boiler leads to exceptional temperature stability and control for the shot; steaming power is phenomenal; redundancy systems built into the machine make it a market leader
Negative Product Points
Mine's a special case - it is a unique machine designed to run off normal household current (110V), and as such cycle times for the steam boiler are very slow, and brew boiler isn't as fast as the 220V versions.
The La Marzocco lineup are the machine usually chosen by the top tier independent cafes in the US, Canada, and indeed, around the world. There are a lot of reasons for this.
First and foremost is the dual boiler system. Independent boilers are inside the machine for steam and for brewing. What are the benefits of this kind of system, vs. the heat exchanger style first invented by Faema and now used in most commercial espresso machines?
Ample steaming power is one reason. The steam boilers in La Marzocco machines are large. In my (relatively) tiny 1 group Linea, it's almost 4 litres, just for steam. Move up to the 3 or and 4 group machines, and you have a massive 17 litres used for steam production through two steam wands, and the power to back it up with fast cycle times, and ample steam at the 1.3BAR to 1.4BAR range.
But the real benefit is exceedingly precise brew temperature stability. La Marzocco machines feature a thermostat in the brew boiler that has a 1.5F cycle mode - if it drops 1.5F off "norm", it kicks in the heating element and cycles back up to the proper brewing temperature that you have dialed in. You can also control the brewing temperature with the use of a screwdriver in fairly precise control - I've gotten it down to maybe 1F with about a 3-5 minute turn (imagining a clock face). The grouphead is massive and actively heated from the brew boiler, leading to a shot that maintains its temperature throughout.
One negative comes from the use of Automatic La Marzocco Lineas (like mine): some brew water travels outside of the grouphead briefly to go through a precise flowmeter for the automatic functions, and if you don't use the machine for a while (like I do at home), you end up with colder shots if you don't do a good flush at the start of your drink build. This is a multi-stage thing - the water outside of the grouphead, sitting there, reduces in temperature. If you pull a shot right away, the water going through the flowmeter and into the grouphead again cools the grouphead slightly as well - you have to run about 2-4 ounces prior to drink building (ie grinding for the shot), then a bare ounce prior to locking and loading the portafilter into the machine to get your precise brew temperatures.
This is not a problem in a cafe scenario where you are doing good volume; short flushes of the grouphead as you remove the portafilter (a good cafe practice) is usually good enough to be within 2F of your optimal brewing temperatures.
Compare this for a moment to the typical consumer or prosumer heat exchanger espresso machine, which uses a boiler for steam, and pipe assembly through the boiler to flash heat the brewing water. The range on most prosumer HX machines is usually .2BAR. I don't know the temp variance off the top of my head for what .2BAR is, but it's probably 10 to 15F difference. So that's your first variable. Let's be fair and call it a + or - 5F variance above or below optimal (so if optimal is 202F, you could have between 197F and 207F influence on the HX). Then add to the equation hot or cold water - new water in a prosumer reservoir might be 65F. If it's been in there for a while, it could be 100F or more. That throws brewing temps for a further loop.
Add the guess work of how long water's been in the HX (and superheated), if the grouphead is actively heated with steam boiler water (which could bring the group up to 230F or more), and you end up with a lot of guess work in getting an optimal 202F shot, start to finish. In my experience, prosumer HX machines can have a variance of as much as 8F over optimal, and 12-15F below optimal when brewing, and it changes during the shot. LM machines don't have this problem.
Don't even get me started on single boiler machines :)
Other excellent points to the La Marzocco Linea include the fact that there's a lot of redundancies built into the machine - mechanical backups and overrides for the electronic features. For instance, if your automatic flowmeter or panel goes south on you, you can still brew using a simple on-off switch for the pump. If the steam boiler dies, you can disengage it and still use the brew boiler. There are manual fill backups for the autofill system for the steam boiler. And so on.
My machine comes equipped with a Procon rotary pump, as do all La Marzocco machines. Mine's a bit different though - a sort of experimental pump that uses speed of rotation instead of torque to get the pressure up - it does this to save power. What's especially cool with almost any rotary pump is that you can control the pump pressure very well.
In fact, one of the things the procon has let me do is experiment more with pump pressure vs. brewing temperature, a variable most home machine owners can't even consider, given that pump pressure is more or less "set" by a check.restriction valve from the vibratory pump found in most consumer and prosumer machines. But with a rotary pump, you can easily dial the pressure up or down, and it's introduced a whole new way to fool with your espresso production - I've noticed that some blends work well with a 9.5BAR pressure rating but a lower brewing temperature, and vice versa. For a coffeegeek, this is pretty cool, but you wouldn't expect most cafe owners to do this, or most home users. Still, if you're looking to super fine tune your espresso experience, any prosumer or commercial machine with a rotary pump allows this experience - where the La Marzocco wins even more is the very precise temperature controls the machine enjoys.
The machine is huge, and not recommended for the kitchen counter. This is a machine that, if you buy it for the home, you want to build something around it - your own home bar (coffee and booze! boooyah!), or recreation area. The machine is well suited for displaying the back to the room while you get behind the machine and face everyone in the room - in my case, it's in a tight spot in the house so the machine's back is to the wall.
Two real negatives for home use - the machine is like having a heater in a large room - it gets very hot, and it heats up a lot around it. Second is that with my experimental procon pump, it's noisy. The pump sounds like a turbo; but I should point out off the shelf procons (which the 220V come with) are much more quiet.
A third potential negative for home use at least, is how to deal with waste water and filling the machine - it needs generally to be plumbed in and out - in for fresh water, out for drainage. I run mine off a water bottle (as does La Marzocco themselves when they go to trade shows or Barista competitions with their machines), and have a waste bucket I empty a few times a week, but if you don't watch these regularly, you can damage your pump and machine by running it dry.
I've mainly talked about home use; that's my perspective. I won't bother trying to write about cafe use, but all you have to ask yourself is this - why do the top cafes in the US (and the world) use La Marzocco machines.... it's because they provide better control, more reliability, and superior shot making ability to pretty much any other machine on the market.
Dealing with La Marzocco and their importer / distributor Espresso Specialists Inc is an experience completely unlike dealing with any other importer or manufacturer. These guys and gals don't just set the bar - they are at a completely different level. You'll be spoiled rotten, and will be disapointed if you deal with any other importer for other machines.
One Year Followup
Wow. Has it been one year since I first wrote this review? 14 months since I took delivery of this machine?
What can I say. Having a La Marzocco in your house is just about as good as it gets in the world of espresso. There's not much I can think that tops it. However, with that said.
The steam boiler was tuned and modified to run at 2BAR; unfortunately it turned out to have an achilles heel - the emergency pop off valve. Only one (rather arrogant) Italian company makes these things (for ALL manufacturers of espresso machines), and though the folks at LM pleaded for them to make one with a higher tolerance (2.2BAR instead of the 1.8BAR version that they make), the company laughed, said no, and told La Marzocco they simply weren't using their machines properly. As a result, LMs, which could easily run their steam boilers at 1.8, 1.9BAR, run at 1.5BAR (still higher than the 1.3BAR most HX machines run at). LM had a custom prototype set of 2.3BAR popoff valves made, and I got two of these beauts... but they failed. So I now run the steam boiler at 1.5BAR and use the standard popoff. Thank you, Arrogant Italian Pop Off Valve Maker. Not.
Can you believe it... probably not: but at times, I wish this was a two or three group machine. I often "entertain" travelling pro Baristi and other professionals in the coffee biz, and I'm even in semi-training for the sometime-in-the-future "Seniors Class" Barista Competition... and I find that my time is slower because I only have one group. Yeah... I find stupid stuff to complain about.
This machine sets the standard for espresso and milk-drink excellence. I can't imagine a more serious, tuned machine to have in the shop or the home. The new La Marzoccos coming down the pipe are even more impressive - all the durability and performance of the existing models, but new PIDs, electronics and super sensitive temperature and enviro controls to give the top notch pro Barista the defining tools for making perfect espresso.
Oh one other thing. In my original review I talked about the flowmeter cooling things down. Turns out I was wrong... at least about the 1 group. In the 2, 3 and 4 group automatics, the flowmeter is indeed between brewing boiler and grouphead. But on the 1 group, it's prior to the brew boiler... so no cold water syndrome. I found out about that soon after writing this review, but I didn't make the correction. I am now.
I love the LM Linea 1 group 110V. It's never leaving me.