The M5OW can go louder with greater bass and mid-range detail. They sound more like real music.
An M5OW/good sub combo sounds better than an M2OW/good sub combo. And M2OW/good sub combo sounds better than just an M5OW.
There is a caveat. You may not be able to control the bass from the M5OW. If all you have is a legacy-style stereo receiver, you may be better off with the M2OW.
Another thing I noticed is the muted shimmer of highs with the M5OW. I don't know why. It could be the larger bass and mid-range presence in my room. It is by no means bad and some may prefer it. Treble adjustment works well for an added touch of airyness/shimmer.
it's a weird thing that even though the M5OW sound better, I miss the M2OW.
