I've got the sennheiser hd 270.
it is not the top notch for music production but my cashflow isn't either so.....
but I can mix and master pretty well with it.
the only problem is that you tend to put to much bass in the track(because of the headphone) , but once you know it it is no problem.
I'd have to agree about the bass on headphones. You have to be careful not to get headphones with some sort of "bass boost" on it. But like you said, once you get used to yours then you can adapt to it.