Shield Plus 9MM with the factory 3.1" barrel.
Same frame with a 4" OR slide with ported barrel I built up (how it's carried now).
Same frame with a Shield .40 S&W slide on it. Shoots as good as the 9MM slides/barrels. Needs a dot optic though. Yeah, modified some 9MM Shield Plus mags to feed .40 S&W. Succes with the 10 and 13 round (hold 8 and 10 .40's). Still working on the 15 round (hold only 11). It's a geometry thing, they just aren't wide enough to give you the same "2 less than a 9MM magazine" you get with the bigger/wider framed pistols).
Same frame with a .40 slide and threaded/compensator installed .357 SIG barrel. Uses the same modified mags. for .40 S&W. I need to pick up another .40 S&W slide so I can leave it as a built up "upper" assembly. Also shoots pretty good.
The old P07 DUTY I bought awhile back.
The old Omega C75 9MM I bought a few months before the P07 DUTY.
My latest project was building up a 5" .40 S&W slide for a 2.0 FDE frame. I highly recommend KKM Precision barrels if you want to turn a gun around. This one was another stripped slide I bought all the parts for and built it up. Best shooting full sized M&P I've got now (out shoots two M&P PC guns I've got.)
All the M&Ps are project guns. So easy to find/buy extra slides, internal parts, etc. Almost like an AR15. Sort of build up what you want. If you find you don't really like it you put part of it away and build up something else.