Are you telling me you haven't heard an M50?!
This picture says it all:
I love the M50, even with my Q701 and AD700 around.
Surprisingly, I find that the M50 and AD700 sound very similar from around 300hz upward. It's something I've noticed since I first heard the M50. They are both warm with slightly grainy, forward treble. This causes harsh tracks to sound nice on them. If you get an M50, I'll show you example songs.
Comparing the bass of the M50 to the Q701, things get weird. They both have very strong, deep bass, but the Q701's bass is more..tactile. This is due to its tightness. The M50's bass is more present, but it isn't as fast and clear..as high quality, if you will. Just more quantity.