These MechTech units are great. I've got one of the old ones in 45 for a 1911 frame; it's one of my favorite guns to shoot. Really easy to rapid fire and stay on target. Of course the first thing I did to mine was get rid of the silly muzzle decoration (they don't even bother to call it a brake anymore). I'm thinking of getting another in 10mm for the G20 frame.
On a side note, I recently picked up a Keltec Sub2000 in .40 for backpack carry, because it folds up, and should give about the same ballistics as a 10mm pistol. It's about the same price as the MechTech (mostly due to demand) but nowhere near as nice to shoot, or as accurate.