I have some Ts100s as well (had originally gotten them for my Atrio MG7) but never thought to try stretching them to size. Do you noticed a change compared to the stock foams? I had thought about getting either the Ts200 or Ts400 to try, but if the 100s don't affect the sound I'll give them a try! I currently use genuine sony hybrids (easily found on Amazon for about $8) and found those to be the most comfortable to date, and I feel they are pretty good at noise cancellation. I've never tried the SE215 so I can't compare there.
Well, I am not a fan of hybrids. I like the seal but it is too easily broken with movement for me. Also they have always itched. I have become accustomed to foams and prefer the seal and isolation I get over any minor sound changes. I am careful though. The Complys I am using are the comfort versions. They are more rounded and shorter than the normal Complys. They have a fairly large opening. I use the large version so they seal a good bit better for me than the supplied tips. The supplied tips are longer and if I insert them deeply they opening is closed off. I thought I had a bad set when I first received them trying the foams. I wasn't getting any sound from the right side and it was just the tip closed off where I had it too deep.
I may try some normal Complys eventually. I have one set of Shure Olives I would like to try as well. They are actually my favorite over the Complys but the opening is smaller and they are harder to stretch. Stretching the Complys is easy and I think makes the tips much more secure than the core mod on the larger Complys. Just my take though. Either would work.