I was at a drift meet last night and I talked to six guys. They all said the Sprint. They say it's smoother and is more tweakable than a TT 01. Even if you're not going pro, it's good to have all that at your fintertips.

The TT-01 is great if you're on a budget.

TT-01 shaft driven: never breaks
Sprint 2: belt drive: better for onroad and smoother but more maintenance. I, however, met someone that said he never had a problem with his belt.