I find my DT880 to be brighter than my T1's. To me the T1's have a lot of treble but it's smooth.
I think the T1 is very bright also and prefer the sound of the LCD-2 (and other similarly sounding headphones, which I have compared here) and was able to control any sibilance issues with source pairing. I was using the RPX-33 as an amp and tried the MX-HUD1, my Audiotrak Prodigy HiFi 7.1 sound card, or modded iPod 5.5g as a source. I had to roll the opamps in the HUD-1 to get the best sound out of my combo (AD8599) to match well with the amp, and the Audiotrak didn't sound great, but the iPod did (which was surprising). I wonder if I would have got different results from the T1 with different amps/DACs and am wondering if I should keep it and try more options or not.