Interesting. I too have run 2.54 for a long time with HT enabled, and no problems. Then comes GS3 and all the problems with HT, and other things. I was wondering about that. I have found GS3 to be a big wash. I'm sincerely glad that it is working for some people, but for me it has been a total waste of time and money. I'm going to return to GS2.54, turn on HT, keep my Powercore, and make some music.
Since getting my ASUS P4C800 E-Deluxe board and 3.2 CPU I've always had HT turned on and never had a problem with GigaStudio 160 2.54. I'm waiting for the next update from Tascam which I hope addresses the HT problem that 3.0 has, before I purchase the $249 upgrade.