Redbeardsong,
I can answer that. I have an SR9c and a M&P 40c. I like both but much prefer the SR9c for concealed carry. Keep in mind these are strickly my reasons. What I find as a preference many others will find a detractor.
First off I'm different than most here in that I have to have a manual safety. personal preference. So,
1) The SR9c has a smaller safety, a stronger safety to click on and off, and the safety locks the slide. The M&P safety has clicked off without me knowing, and I don't notice until I take the gun off my belt at the end of the day. Also sometimes when I place the M&P in its soft leather holster on my belt I have to be carefull not to rack the slide, even just a little which could present a problem in a emergency situation if the slide isn't completely closed. My hat is off to Ruger for locking the slide with the safety on.
My other reason for liking my SR9c better than my M&P was because I ordered the M&P and didn't realize until I got home that the one I received had no Magazine safety disconnect. Another feature I prefer that most don't. This was strickly my fault since it could have been purchased with this feature.
Now having said the above, let me also say; the M&P feels great in my hand, shoots well, and is a great looking pistol in my opinion. Ultimately you must decide what features you prefer. For me it's the SR pistols.
