I tried the X TT at Nurb last night and gave up...I'm usually pretty persistent too. Although, racecars on RS tires are not at the top of my list of things I like to do in GT, so I don't have much experience with those grip levels in general.
Using a DS3, I just could not come to grips with the handling of the X. Actually not the handling of the car, but more the way the game was interpreting my inputs or something. The throttle and brake control was alright, but the steering was all over the place.
Felt like there was a huge deadspot near the center of the stick's motion. I tried gently applying slightly more and more steering lock, and got nothing - nothing - nothing - FULL LOCK!
I don't know if it's supposed to mimic some sort of progressive feeling due to the massive downforce available as speed increases, but it felt terrible on the DS3. Maybe I'll try some different controller sensitivity settings, but I dunno...
Haven't tried the others as I was so turned off

I'll give them a shot this weekend.
I also have to go back to try to lower my time on the SSR5 seasonal. About a second off G's Xbow...but I'm guessing Amemiya-San can work some of his tuning magic and squeeze more out of that RX7
