I've been carrying an M&P9c for about a year now and it's been great. My first pistol was an XD9 service and I really, really liked it but the XDsc just didn't appeal to me since it seemed really boxy. The M&P took a little getting used to since the controls are a little different and I didn't like the plastic "broken" M&P trigger, slide release positioning, lack of grip safety, and lack of extended magazine sleeves.
I've been so focused on NFA stuff lately that I didn't even realize SA released this new XDm compact a few months ago, causing me to miss out on the 3 free mags deal
. I went to a local shop to check one out and had to have it! I sold my XD9 service, ordered the XDm9c, and just picked it up today. Unfortunately I wasn't able to make it to the range today but I don't doubt the XDm will perform very well. Once I get a few hundred rounds through it, it may replace my M&P9c as my daily carry piece.
A few things I noticed that may be of some help to others considering these pistols:
Overall size is nearly identical. The XDm9c is about 5/16" taller, .03" wider at the widest point of the frame, .01" narrower slide.
The XDm compact slide is slightly longer, the slide release is a little farther back, and has an ambi mag release. The M&P has an ambi slide release, reversible mag release.
M&P9c on top of XDm9c, the XDm9c is taller by the thickness of the mag baseplate, .25". Sights are very similar, the M&P9c is ~2oz lighter empty
The grip angle is very similar though the M&P's mag baseplate is not parallel to the slide. M&P9c is 12+1, XDm9c is 13+1 with flush mag or 19+1 with extended mag
Both have 3 different backstrap choices to fit your hand. The M&P9c's grip is a little more rounded, less aggressive, and a bit more comfortable IMO. I'm waiting for PRP to come out with rubberized laser cut grip decals for the XDm compact. The XDm has a chamber indicator on top of the slide and a striker indicator at the rear of the slide to aid in identifying a loaded gun. The M&P has a small "window" at the rear of the barrel that lets you see the rim of a chambered round. The XDm series all have grip safties and the M&P compact is available with a manual thumb safety(which I removed from mine).
For me, the XDm9c is the best of both worlds between the M&P and XD series.