I have a Glock 19 and a Shield 9. Although the Shield isn't full size I have had problems with double feeds and other FTE's. I tried all different brands and weights with the same problem. I sent it back to Smith for repair and it was returned with a new barrel and extractor. Fired another 100 rounds with no problem. The Shield feels better in my hand and the frame is reinforced and feels better built. I shoot the Glock pretty well but the grip is not at all comfortable. The reason I haven't bought the full size Smith 9mm is due to the bad experience with the Sheld.. Any thoughts? Thank you!!
Several thoughts, actually.
Firstly, if the Glock isn't comfortable in your hand, then end of story. There are plenty of 9mm's available that are good, reliable shooters AND comfortable in your hand.
Secondly, discounting the M&P9 full-size simply because you had a bad experience with the Shield is simply irrational. You know this, right? There is no "cause and effect" relationship here; that is, it does not follow that having purchased a defective Shield will result in purchasing a defective M&P9. So, cast this notion out of your mind, okay?
I DO believe that the M&P9 full-size is a worthy candidate for a 9mm, and has much going for it: great ergonomics, reliable and accurate shooter, lifetime warranty, USA manufacturer, lots of available accessories, and consistently named on "Best 9mm" lists. That said, you may also want to check out the Ruger SR9, which also ticks all of the previously mentioned boxes.
I hope this helps. Good luck!