The FB70 is a great buy if you have a place to showcase it, otherwise get a Linea. Buy new from an authorized reseller to save yourself a lot of hassle.
Positive Product Points
Same superior internal construction as the LM Linea, but the outside shell is beautiful and is a great addition to a coffee house if it can be placed in a way that the customer can see the back of it.
Negative Product Points
The outside appearance may not be worth the extra cost if you have to pay full list price for it. I don't know of any extra features that it has that the Linea doesn't other than extra insulation because the outside shell is ABS.
Detailed Commentary
Either the FB-70 or the Linea is an excellent choice for any coffee house if you want to make the best espresso. The feature that makes it one of the best machines to buy is the dual boilers. It also has a few extra features that other machines lack, such as the ability to do maintenance on it without taking it out of service and extra room under the portafilters so you can brew directly into most cups. The extra height makes it easy to clean underneath. La Marzocco needs to come out with some new features, like digital controllers and better heat management, at least as options, to give people more reasons to buy new rather than used. For the ultimate combo, get a La Mazocco Swift grinder for even more consistent espresso. Also don't forget their excellent troubleshooting guide (the big orange book.)
Buying Experience
I bought this new from an authoized reseller via Ebay, but ESI refused to honor my waranty because the seller sold it at too low of a price.