Both of mine were mid 2012 test fire dates. From the research I have done, it seems to be only the full size 9mm with accuracy issues.
The fit between the barrel and the slide was so loose on one, you could make it rattle when you shook the slide when it was pulled off the frame. I'd say it had a few millimeters of play in a circular motion. The pistol struggled to stay on a 12"x 12" target at 25 yards no matter who was shooting it. While I'm no bullseye shooter, I have had a lot of pistol training, have competed in steel shoots and am shooting pretty much weekly.
Storm lake makes oversized barrels for them that need to be hand fit to the slide to correct the issue, but it's not cheap. S&W doesn't seem to care to fix the issue either. They sent me a new slide that was just as bad.
In comparison with my HK P30 and Glock 34 I can put 10 rounds inside a 6" birch wood Casey shoot n see target at 25 yards. The HK barrel locks up as tight as a drum and from what I've seen reported, it's probably the most accurate out of the box duty pistol on the market.
In the end I didn't feel like spending an extra $400 to get the M&P where I wanted it so I went with the HK.
Oddly enough I had a much harder time getting mags for the M&P as well. While people always seem to say HK mags are expensive and hard to find, I called up HK USA and ordered 5 mags direct for $35 each. I had seen them online as high as $60 each and they were out if stock. Most people forget to call the manufacturer first for mags and parts. Also unlike Glock, you don't have to be an armorer to order parts direct with HK.