In my opinion (and a friends, who may voice his own opinion or may not...he's been busy), the HT2 TL's are a more solidly constructed speaker, thus probably less resonant. I am not saying the ST's have audible resonance, but I can safely say the HT2 TL's minimize it as much as possible, probably to the point that it plays no role in the sound you hear. I'd like to think the ST's do the same, but I won't know for sure until we have the comparo. I love my ST RT's, and I hear no resonance, but who knows.
As far as the differences in sound go, we both felt the HT2 TL's major difference is in the bass department, while maybe having a slightly better midrange (detail and resolution). We're talking maybe 5% here. Under blind conditions I'd bet hardy anyone would pick up on the differences, especially if the speakers were level matched and set up in the same position (we need one of those Harman speaker shufflers
Would I take the ST RT's over the HT2 TL's? No. But if I had a subwoofer or two (which I do), it might be a different story. I will say that the HT2 TL's fill a large room easier than the ST RT's. And the bass - WOW! In my buddy's room I'd swear they go flat to 25Hz or so, which is enough to not
need a subwoofer for music. So for strictly 2-channel purists, it's a no-brainer; HT2 TL's all the way! Period.
Hope that helps. I am waiting on TJHUB to find out when we can have the comparo. He's been busy, but hopefully it will be in June. And hopefully the others will be able to attend as well.