I just picked up a couple pairs of these today at my local retailer (had them match the MF price).
Quicky review is that they definitely isolate very well! Even though they are bulky, they are comfortable, and fit snug (probably won't slide off a drummer head). The phones themselves seem very rugged, but I'm not too impressed with the whimpy cord, and the 1/4" adapters don't fit very tight ,so you may want to replace them with something better. Actually, one of my adatpers is so loose that it causes a short, and makes the headphones do goofy phasing, and cut in and out.
What's interesting is that the two pairs I have sound a bit different from each other...They differ in the midrange (not by a huge margin though). If I compare them to
my Sony MDR-7506's they are much less hyped in the highs and lows (which might be a good thing)...I would say they are a bit sterile sounding by comparison. Certainly not as good as any pair of Grado's or the upper end Sennheiser's, but these are not designed to be great sounding headphones, they are designed to isolate you from the environment, which they do very well! I think they are worth the $89 I paid for them, but would I would not recommend them if you're looking for "listening enjoyment" cans. If that's what you're looking for, then Grado or Sennheiser would be the way to go.