HD800 is on another level at all times. The T1 is a terrible headphone, or more precisely, a 'me too' headphone that performs worse than every other 'real' Beyer. The T1 has a very high noise floor, rings like crazy, has high distortion and in relation to the question, is drier and has a rough spikey treble. There's a reason the hype train on the T1 hasn't survived over the years.
I didn't mind the T1. But agreed the HD800 is a lot better.