...pitch and velocity randomization to avoid machine gunning...
On this, I'm thinking of updating my sfz mappings to add a little more - with pitch on the drums having some randomisation (+/- 10 cents max) and, within each sample region, having velocity adjust the pitch by +/- a cent (based on the region velocity mid-point). Using LH/RH alternation pretty much eliminates machine-gunning, anyway, but this could add a bit of extra variation. (I have mapped my TrapKAT pads to send alternate LH/RH hits for everything but the snare, where I use two pads. I use enough kits that don't get GM or V-Drum mappings "quite right" that I usually map my 'KAT to their default...)
I got the numbers by checking three tom strikes for how much pitch variation there was - it was way more than I expected - nearly a tone and a half. Of course, it's not just how hard you hit - it's exactly where you hit the head. I guess if I knew how position-sensing triggers worked, I could map for them, too.