First impressions: Trigger was VERY gritty straight out of the box and just generally all around crappy feeling until I stripped it down to clean and lube it. Now it is noticeably better but still a bit less than perfect. I hope it will smooth out even more with shooting.
I have very large hands but oddly enough, I find that the smallest grip insert "feels" the best right now (shooting may change my mind, of course). With the smallest palm grip, the MP closely approximates the slim, comfortable feel of my XD-9.
Another interesting tidbit: The MP40 fits the C-TAC holster for my HK USPf 45 snugly enough to be useable.
By the way, why is the trigger hinged? What purpose does that serve?