I've just got the Momentum over ears - I primarily listen to drum & bass. The momentums are not ideal in my opinion, forgive my terminology as I am not up to date with the audophile lingo but my personal opinion of them is that they work very well for deep lower frequency bass, however they lack in mid range bass. The rolling mid bass break downs just don't have enough "punch" at lower volumes leaving something lacking from a lot of the tracks.
I will keep them for a few weeks but probably sell and try the M-100, they don't seem to have any resellers in the UK for them though. The momentums I bought used so paid a reasonable price so won't lose much money if I decide to sell them.
A lot of people have described the momentums as having great bass, which in parts they do, but I think a dnb head will be disappointed by the relaxation of them, just not enough punch in the middle. To get the punch you want from a dnb track you need to turn the volume up too high, or EQ the bass up. Which is a bit of a hassle on an iPhone.