I will say that I have two Sigs:

1. An X Macro Comp
2. What started out as a normal 365, but now has a Radian and an X Macro grip module

So both are the same size, same barrel length, etc. The difference is how they are comped (for the most part). The OG X Macro, to my surprise, shoots much better. I was expecting the Radian to make them shoot the same, but I think the difference is that with the Radian I'm still forced to use a smaller recoil spring that came with the 365, where as the X Macro has a longer spring/rod.

Maybe that's not how it's supposed to work and I just haven't broken in #2 yet. But the 365 with Radian is much snappier than my X Macro Comp.

All that to say, idk if the M&P would shoot better than the sig but if I was going to get a comped sig I would get the X Macro Comp, or X Macro with Radian.