First time I've heard about 550s not doing too well in mid frequencies.  Mine perform very well all around and in mid frequencies especially.  You can usually find them used for very cheap, I got mine for $110 on ebay buy it now.

I would add AKG k550s to your list of things to look at.  Cable length and comfort are nice, and the whole thing is an overall step up from my ath m50s.   Hope it helps.

No experience with those, bur I recommend putting the beyerdynamic dt990s on that list. They've got a nice slight v shape to them and work well with most genres.

The DT pads are not compatable with the Vmodas, but they are comfortable enough to begin with.

Sennheiser HD 439s are pretty mid focused and fit most of those categories.   Also look at Koss Pro DJ100.

Look for Vmoda crossfade lps for around that price.  Nearly indestructible and they sound better than beats. 

Had a beats user at my school appreciate the Grado sound.   Also knew what my portable amp was without me having to explain.    

Cannot comment on the others but melodic death metal sounds damn good on gr07s.  They're pretty well constructed too.

Metal fan here.  If you can make the jump, I'd go for vsonic GR07s. got to try a pair of my friends recently, and they are just stellar.  Well worth the price.

I bring HD598s and K240s to school all the time, people usually only ask about my E11 though.

Happy to help

Sonic preferance? Do they need to be bluetooth?  Are they going to be used at home or on the go? Do you have or plan on getting an amplifier?

Try posting on the recommendations thread http://www.head-fi.org/t/529144/full-size-headphone-recommendations-thread-i-e-dont-start-a-new-thread-ask-for-advice-here-please-read-op/29250 where there's more traffic   I'd suggest looking at V-Moda Crossfade M80s (<$200).  Not the most comfy but...

Agh, I've yet to encounter that, as all my current headphones are one-sided. But that's a terrific solution

Quote:   I don't believe it matters between the two, and either way, they wouldn't be supporting more weight than they can handle