OK, I just fired up my M80 (been a while) and I take back everything I said above. The M80 is actually just about as bassy as the MOE with better mids and actually pretty similar treble. The M80 definitely has a better sound stage and is also more comfortable than the MOE. I will have to do some more tests but I may just go back to using the M80.
So I will watch the comments from those having both. If the XS manages to be more detailed with as much or slightly more bass and more airy extended treble as the early reviews indicate I might buy a pair.