Zuqi
100+ Head-Fier
I love the unique look of the chrome SR325i, those are relatively rare, no? I have the gold 50th anniversary Grado SR325i, and also the Alessandro MS2i, which have the brushed aluminum cups.
Interestingly enough, even though I've read a lot of negative impressions of the T90, often complaining of murderous treble, I've been leaning towards getting a T90 because I read the same things about the SR325i before I bought it and I love those. Like you, I think I'd appreciate the enhanced comfort and bigger soundstage and better instrument separation of the T90.
Just a little bit of information that may help. I owned SR325is, not i, I would classify its sound 'bright and energetic', which casue fatigue after around 30 minutes listen. I also owned the T90, which I would describe its treble 'ear bleeding painful', I can barely listen to them more than 5 minutes. It's even sounds overly bright with a Woo audio tube amp.
I'll put it this way, if Sr325is' treble is like a serve of slightly burnt barbecue, then the T90's treble is like an animal corpse after a forest fire.

Byerdynamic's new headphones, such a s Amirion are DT1990 are much better headphones. But if you are still curious of the T90's sound, I would recommend you to try it in a hifi shop first if possible.