The XB500s are definitely one-trick ponies, with a ton of bass emphasis. They probably won't sound all that great with Coldplay, or really anything where you don't want overpowering bass. They also might not work too well for gaming. For $150 you can do a lot better. Something like the M50s or HFI780/580s would seem to fit your bill quite well. Shures might be a bit too neutral for your tastes, if you were looking into the XB series. For $200 you could get something more portable like the HD25-1s or M80s.
So the Audio-Technica M50, Ultrasone HFI780 and HFI580?
Apparently the 780s are "too harsh"?? What about the Ultrasone DJ1 S-Logic Surround Sound Professional Headphones??
And NONE of the Shure sets would be suitable? just wondering because of their reputation..
BTW any thing about the V-MODA Crossfade LP headphones?? They look alright :P