I use Torco religiously. However, if we had access to actual premium fuel up here, I would use that. My dealer sells the Torco "race fuel" and has zero problems with using it where warranty is concerned. We only have access to 90 up here and the computer pulls timing, making for tangible power loss.
Now, I'm no engine expert or fuel additive expert but the best 0-60 I could muster with my trackhawk was 3.8, over and over again. Added a 16oz can of torco and drove around for awhile so it could mix in the tank. Same weather, same place, I had no problem ripping off 3.5s over and over and over. I don't run it in the winter as there is no point due to road conditions and I just let the computer do it's thing. Come summer, it's in every tank and it really was a noticeable difference in not only feel, but also time.
All that said, if I had access to better fuel, I would absolutely go that route.