So I unboxed and hooked up the 353X today. It is smaller and fits better on my little nightstand setup, isn't hot when on, and the plugs are way easier to unplug, so just what I wanted.
I haven't done back to back comparisons with the T1S but just going from audio memory they seem really similar in sound. Besides the fact that the 353X gets a little louder, I didn't really notice much if any difference with the L500 and 009S (maybe slightly smoother fuller mids on the T1S but then again that could just be me imagining/focusing on it, certainly not a major difference I can chalk up to being an actual difference without further comparison).
However, I did use this as an occasion to bust out the Ω again. I'll have to do back to back comparisons to be sure, but the Ω does seem a little less darker on the 353X than the T1S (beyond volume). It's still a darker signature than the 009S, but it's gotten closer what I assume my preferred tonality would be. I used to think that the timbre on the Ω was the most natural compared to the 009S (and now L500), and now it seemed even better because it wasn't as dark. Still, I'm pretty sure I prefer the 009S over the Ω after doing a bit of critical listening, It has a less realistic presentation, but it's just more enjoyable. Sort of like how the I prefer the CD3000 to the R10, the latter has the most natural timbre of any phone I've heard, but the CD3000 has a bit more sparkle on top and just better with most stuff.
Aside from the tonality differences, they're pretty similar phones. The Ω seems to have a little more diffusiveness in the soundstage/imaging whereas the 009S has more precision, though it isn't a great difference (and maybe I'm just influenced here by the darth_nut review). The 009S actually even seems a little less veiled and more transparent than the Ω as well which I find surprising, though this might be due to the Ω being darker (I don't think the 009S has any better clarity than the L500 for example, both are as good as it gets, maybe the Utopia was as good but I never got the chance to compare directly).