Welcome!

I would definitely talk to CS about your M3's. You know somewhere down the road, those small things will end up nagging at you.

I have M3's as well, and do agree that some percussion end up sounding a little fat sometimes. Are you listening to the M3's in the nearfield? I was thinking that you could try and reposition them in the room to see if it makes a difference with the slightly muddy bass, but usually the listener is close up with computer speakers so the room is less of a factor.