Consistent grinding with minimal ground retention, neat, compact, reasonably priced.

Stepped adjustment too coarse for espresso,  too much plastic.

I was looking to upgrade from a Solis Maestro Plus that I'd used for three and a half years.  I grind per-shot, alternating between different blends and decaf for my wife.  I wanted a grinder that offered consistent/reproducable ground fineness and minimal stale ground retention.  I was also aiming for convenience (hands-free operation, neat, quiet, compact) and good build quality.

I decided early on that I didn't want a doser - although some people seem to swear by them, I don't think it makes sense for grinding one shot at a time.  I was willing to pay for one of the higher-end doserless options (e.g., Rancilio Rocky, Macap M4, Mazzer Mini E), but I ruled them all out based on one or more of my criteria: They all seem to have significant ground retention, and only the mini E offers hands-free operation.  I tried out and returned an Anfim Haus (essentially a doserless Pasquini Moka), which had horrendous ground retention and neatness problems.  Eventually, it came down to the Virtuoso or the Versalab M3.  Ahhh, if only money were not an issue...

I've now owned the Virtuoso for almost exactly a year.  Here's my breakdown of how well it satisfies my criteria:

• Stale ground retention: Excellent (i.e., minimal) due primarily to the conical burrs which lead directly to a near-vertical grounds chute.
  
• Grind consistency/adjustment: Fair.  It is significantly more consistent than the Maestro, presumably due to the beefier burrs, and the improved 3-point mounting arrangment for the top burr.  But the stepped adjustment increments are far too coarse: it is quite common that I have to hold the hopper between two settings.  And although it could probably convert it to stepless (if one could rig something toprevent the hopper from rotating during grinding) the adjustment wouldstill be overly sensitive.
  
• Hands-free operation: Mixed.  The grinder has no portafilter fork, so grinding directly into a portafilter means holding it for the duration.  There is a pushbutton on the front face that can be held down with the thumb of the same hand, so at least the operation requires only one hand.  But if you (like me) prefer to have both hands free, and/or prefer to keep the portafilter heating in the group head until you're ready to tamp, you can opt to grind into the plastic grounds bin.  In this case, the grinder may be started/run from a timer switch on the side, which I find quite convenient.
  
• Neatness: Initially poor, but excellent with modification.  The grounds bin has had severe static problems, despite the fact that this is a replacement bin, sent out by Baratza to purchasers of the first batch of grinders.  Grounds literally leap from it when I remove it from the grinder.  So I developed an alternative solution, cutting out the front face of the bin (with a dremel tool) and epoxying two "rails" onto the interior sides to support a small grounds cup, which can be easily slid in and out.  The top of the cup is slightly smaller than my 58mm portafilter, and so transferring grounds is virtually mess-free.  
  
• Quietness: Fair.  the grinder seems a bit quieter than the Maestro, but not much.  I find it difficult to continue a conversation while standing next to it.
  
• Compactness: Excellent - it's as small as one can expect.
  
• Build quality: Fair.  Although it is much heavier than the Maestro, the Virtuoso has more plastic than I'd like.  I don't mind the mostly plastic casing (and wouldn't expect more for this price), but the burrs are supported by a nylon threaded ring that seems to have a fair amount of flex.  For this reason I don't expect it to last more than a few years.
  
  

In summary, I'm not sorry I bought the Virtuoso. The conical burrs are the main positive feature, allowing for minimal ground retention and consistent grinding at low speed (600 rpm).  And although I assume it sacrifices some grind consistency/adjustability (as well as quietness and build quality) compared with a Mazzer or Macap, it excels in neatness, size, and cost.  Nevertheless, I'm still dreaming about a much better home espresso grinder:

• conical burr set, and near-vertical exit chute to minimize ground retention
  
• stepless adjustment, but with a "quick release" to allow rapid large adjustments (e.g., for press-pot)
  
• three interchangeable grounds receptacle options:
    - hands-free portafilter fork
    - metal (static-free) grounds cup, with supporting holder
    - larger grounds bin (for drip/presspot)
  
• two hoppers
     - normal-size hopper, with shutoff gate
     - mini-hopper with built-in adjustable measurement device for dispensing single, double, or triple doses of beans
  
• rocker switch or timer (pushbuttons are not hands-free)
  
• sound-dampening mounting of motor/spindle
  
• solid build quality, but need not be fully commercial (e.g., good  for 10 years at 100lb/year)
  
• as compact as possible
  
• under $600

Kyle and Kyra at Baratza were great.  Shipment of the first batch of grinders was a bit delayed from initial projections, but they kept me informed by email.  When it arrived, they were very helpful in providing re-calibration instructions.