To start - the grind quality. This grinder is very consistent, noticably more so than the Solis 166 / Starbucks Barista grinder which I use at work. Upon first receiving the machine, it was too coarse on the finest setting, and I needed to adjust the zero point (easy). The range is usable from press down to espresso, but turkish would be a stretch. I have found that my shots still vary based on my tamp and machine temp, so I will post back on whether or not the grind adjustments are sufficient in a followup. Currently, I go through a pound of Zoka in 1-2 weeks, and turn it a notch finer around day 7-8 as the beans dry out - that's all the grind adjustment I make at the moment.
My personal strongpoint - less stale grounds. I was very close to buying a doserless Rocky and was glad I tried one first. I did not like the amount of coffee that was left behind in the burrs and chute, and didn't want to go through burning a few grams of beans to get the stale grounds out each day. The Virtuoso drops them straight down from the burrs to the bin, and I can't shake more than a few grounds out of the chute. I took it apart after the first week, and there were very few trapped grounds, a fraction of a gram. The first shot tastes as good as the second.
The antistatic properties are excellent as well. The grounds pile up nicely in the bin - they don't stick to the sides or in the vertical chute! I pour my coffee into my portafilter without any hassle, no scooping or scraping grinds from the side. A very small amount gets stuck in the corners, but one or two light taps clears them. After pouring the grounds out, I just tap the bottom of the grind bin once over my knockbox and all the grounds are gone.
Product support was great. Since I had one from the first manufacturing run, I needed to readjust the zero point for the grind. I contacted Baratza, and worked with Kyle to readjust it. I happen to be just a few blocks away, so I stopped by and Kyle showed me the procedure in person (it doesn't get better than that!), which was beyond what I was expecting.
Inside - I had the luck to see the Virtuoso and Maestro insides, side-by-side. The Virtuoso is a similar design to the Maestro, but has some serious improvements. The burrs are better cut, and sharper. The carrier is a huge improvement - the Maestro burrs could wobble slightly during grinding, which led to uneven grind after machine wear. The Virtuoso has a different carrier design that is much more solid and adjustable. You can't tilt the burrs, they are held very firmly in place. The motor in the Virtuoso is also larger, and has a better gearing, making it a bit quieter than the Maestro. The heavier cast base on the Virtuoso also makes the machine more stable, it doesn't slide around the counter and stays firmly in place while you use it.
Background: I came across a good deal on a Gaggia Classic, and spent a few months drinking preground Illy while researching grinders. After trying out a Rocky, which was the top of my list, I wasn't satisfied with the amount of mess and grounds left behind in the chute and burrs. I waited until January for this to ship and it was worth the wait! The only downside I see is that a stainless grinder would look better next to my stainless Classic.