Jaay, Pearl just licensed the DM10 from Alesis and rebranded it. Same story with the cymbals (they're Smarttriggers). About the only R&D it appears they did is with the pads -- they retrofit existing acoustic shells and actually look pretty intriguing.
The video on this page details these features a bit more: http://www.steveweissmusic.com/category/pearl-e-pro-live
Overall the module sounds a little dated to me, but near the end of that video they showcase an imported Toontrack kit, which is *very* nice to my ears.
David, it looks like you can only import one VST-based kit at a time, i.e all 128MB is taken up by ONE kit. Slightly less than flexible in that case :/ ... and even still the samples would need to be highly compressed and dithered. Still, does sound pretty good on that video.
I really feel we're on the cusp of big changes here with modules. The limiting factor is really just the cost of flash ram. Now that SSDs are becoming mainstream though, those prices are starting to plummet. It probably won't be too long before 64 or 128GB of ram in a stand-alone module will become standard fare. Given the long development cycles of these machines, if I were Roland/Alesis/DDrum/Yamaha/etc, then that's the sorta specs I'd be targeting with my R&D right now, safely assuming the costs would come down in a year or two.