Here's a footnote:
The Virtuoso Preciso comes with the metal gear and, yes, I stripped two of them (back to back) with some lightly roasted Ethiopians on an espresso setting of "9". This is a very hard bean and roasts very unevenly. My guess is that one of the lighter beans was hard as a rock and did the damage.
As always, the folks at Baratza were very responsive and accommodating...