I had the opposite experience from alleycatdad. I could push the T63 very hard on the street, as in going on a sportbike ride on twisty WI backroads, while keeping up with R1's and Ducatis. The TKC80, with it's taller knobs, will squirm and walk a bit at the same pace.
Plus, the T63's are cheaper!
Enduro Racer & Google Earth Adventurer