A lot has to do with the DAC/AMP used as well, as I'd recently discovered. My HD800 and Beyer DT990/600 are generally said to be somewhat bright, and if the source has lots of high frequency, they would sound a tad bright for most. Now, the iFi Micro iDSD (will be getting a Nano iDSD + Micro iCAN in a week or two) has been described as having a neutral sound that tilts somewhat to warm. With the iDSD + HD800 (and DT990/600), I don't find the cans to be bright at all, oh for sure the treble is there but doesn't annoy at all, quite pleasant actually.
With the HE400i which is said to be neutral, I find the sound to be veiled, treble and mids seems to be somewhat recessed, more so on the treble. I'm returning the HE400i, NOT because of this (plugging it in directly to my Asus Xonar Phoebus Solo or SB ZX resolved the veil issue) but due to a cosmetic defect that put me off. Will prolly get a HE400 instead as I understand it to be somewhat V shaped, the iDSD should lessen the treble while I don't mind a little 'oomph' bass-wise.
I've been trying out the DT990/600 and I'm actually quite taken with the sound, mild emphasis on the bass and treble, good soundstage (less width but good depth....at least that's how it sound like to me). As for comfort, I find the DT990 to be very comfortable and light and I can wear it all day long (I do have a rather small head as I'm Asian). I can only imagine what a T1 brings to the table....I can get a T1 for about 600USD and am considering that as well instead of going with the HE400. Thing is, I'd like to try a well regarded planar mag cans and it seems I'm left with either the HiFiman HE560 (and higher) or Audeze LCD2 (and higher). I already blew a wad on the HD800, so the thought of blowing even more is somewhat.....daunting.