I've never handled the M&P but I own a GSG. I've had it for a few weeks and have put 500 rounds through it so far. I've had about 6 FTF with American Eagle ammo. No problems with CCI mini-mags. I actually did not mind the FTF because it gave me a chance to practice Tap/Rack/Bang drills (better drill than with dummies+unexpected). I love my SA .45 and nothing beats the feel of a 1911 in my hands, so the GSG is the perfect .22 for me.
Yes, the finish on the GSG is crappy. I've done all my shooting from the holster and the slide's finish is getting a beating. But I don't care, I'll have it redone one day. Until then, I intend to beat the sh*t out of it.
If you have the chance, try both before buying. And if you end up not liking the one you get, you can always sell it on the EE.