I had the NE-7M for a year, I used it about 12 hours a day. It broke three times (I think from the more than average usage) but the guys replaced it without a problem every time.
I got the NE-700M on the first day it was offered. It looks sturdier for sure!
Sound is good, although I think the NE-7M was clearer. I might have to blame the sony tips for that as the 700 tips look bigger than the 7 tips.
The microphone - it's huge, it's round but it has to...