I've listened to them for a good amount of time. My friend bought a pair of red studios at best buy for 160 via a friend who worked there. Het let me abx it for a couple days against a couple other headphones that I had at the time and a friend's headphone.
M50 > Beats. M50 sadly doesn't beat it out much on soundstaging, but has better clarity and noticeably less distortion in the upper mids to lower treble. The Beats pound out that midbass much harder when called for, but the M50 delves deeper into the bass than the Beats do. The M50's build quality is far superior.
Pioneer HDJ-500-K = Beats. You might as well buy the pioneers. Both offer a bulked up midbass and go decently into the sub-bass, both offer a subpar clarity in the mids to lower highs. The pioneer tends to get more sibilant than the beats in the highs, as the beats are overall more warm. The soundstaging on the pioneer however is better, and that artificial treble boost it has can it times make sounds sound noticeably more clearer. The beats might have a slight nudge towards build quality, but I could see both breaking pretty fast, as they're both very hollowy-plasticy feeling.
Denon D2000 >> Beats. There's nothing the beats have on the Denons besides portability. The same was true for the M50, although the M50 is just as portable as the beats. The Denons' comfort is a far step up from the Beats, and their build quality is better-- despite the screw issue a lot are reporting.
Edited by TMRaven - 1/4/12 at 8:57am