-I have never tried the Urbanite XL, but the M50s are just... Right, more or less. If my memory serves me well, they had a slight bass boost (Nowhere near enough for bass-heads to approve - which makes it just right for me!), with mids and highs which were pleasant and didn't really draw attention to themselves in any way - just a great all-round headphone.
Undoubtedly there are lots of others which would fit the bill just as nicely - but I wouldn't know about those, I have only tried a very few sets of headphones for long enough to have an informed opinion of them.
short problems with ath m50. the guitars did sound off, something much too much around 7khz, problems with ear natural resonance.
-bass was off also, something too thick
-the entire sound was veiled, much worse than similar priced headphones
-they are very expensive for the sound, i think that in america they are much cheaper, in romania they go for around 200$ even more... at 200, there are far better options from sennheiser and ultrasone, again i think that it is for my country only.