I've owned one of the new Model 40s, a blue one, for about a year. It's a pretty little thing.
I shot a few hundred rounds with it the first week I had it, and found that the grip safety was bruising the bone at the base of my thumb. I got a Tyler T-grip for it, and that pretty well solved the problem.
I also found that my gun came very stiffly sprung from the factory, including the spring for the grip safety. At the direction of a couple of guys on this forum, I clipped 2 or 3 coils from the very stout grip safety spring (the safety comes out easily after you remove the grips), and now it takes just a reasonable amount of pressure to depress the grip safety -- still more pressure than required for the grip safety on my 1911.
I also put a lighter Wolff rebound spring and hammer spring in it. That sweetened up the trigger pull, and not once has it failed to go boom in the couple thousand rounds I've shot since then.