Been a Beyer guy for a while, just picked up a set of T1s, which are stupidly good IMO. Might be the best sub-$1k (street) headphones for rock and metal I've ever heard. Enjoying The Diablo Swing Orchestra's Pandora's Pinata at the moment, and although it isn't the best recording ever made, it's still every bit as fun and engaging as it ought to be.
Got to hear them side by side with the HD800s at a meet on my system with music I know well, and I was kind of flabbergasted by how thoroughly the T1 trounced the HD800 in texture and tone... The HD800 just sounds considerably off to me with guitar-driven music. Horses for courses. The T1 suits me quite nicely, and if you haven't heard a set yet, don't deprive yourself of the opportunity!! An utter steal for what these can be had for on the used market these days IMO.