As an owner of the M-100's, I can easily say they're one of the best headphones I've ever heard. They aren't "neutral" by any means, but it's not a bad thing. the words I would use to describe them would be "Clear" and "Fun". The mid-range and treble work wonderfully together, and the bass punches and kicks in all the right ways. With proper amping, these can be the perfect "basshead" headphone, but they work amazingly well with jazz and acoustic as well. The only genres I find they are "comparatively" weak in are badly-mastered rock, and classic, but that's only compared to how amazing it is with other genres.
If you want a "do it all" SQ headphone, but want some great, controlled, deep bass, then look no further than the M-100.
I would also recommend adding the AKG K267 to this little shootout, as that is another headphone I have ordered to compare to the M-100's. If you don't want to add it, you can always check the link in my signature for a full closed portable shootout.