Very Very interesting Jim! I may be imagining it, but at least for the basic rock groove I am listening to, the RD performance feels very real to me including even a real actual room sound, where as the same in EZDrummer 3 feels machine-like even though the sounds are audio samples. There is a "humanizer" function in that program which I suppose introduces an algorithm of irregularity into the playback. Or.... I am completely biased and hearing what I want to hear.

Too bad we can't take a peek behind the curtain - I bet it would be fascinating!
Edit: that video was pretty interesting and while it did not show black box techniques, the story line was interesting as was his playing!
Zane Carney on BIAB