TP hubs are really only good for bmx style applications. They don't work well for DH/XC/AM stuff. They are pretty draggy, and they don't hold up the best for extended, high torque, sit and pedal up a big hill type situations.
Woody has a true precision/stealth hub and rides it single speed with a tall chainring on a downhill bike. He's had it for six years or so. I don't know if he's ever maintained it. I'm not aware of any problems he's ever had.
I don't notice any drag when I ride his bike, not with the silly belt nor the chain he had previously.
A friend of mine used the TP hub for a while. He had alot of issues with the bearing regularly seizing, and TP ultimately gave him his money back with the understanding that maybe their hub wasn't best fit for our unusually wet conditions. That was 4 years ago though, and it's possible they've improved their product since then. Cool concept though.
Extended high-torque engagement (think long climbs in a low gear) can notch the driver. As Sandwich noted, I use one on my 1 speed dh bike. Had it for years. Only re-greased it once because I had the bike apart anyway. I consider it to be the nicest made hub on the market, but it's not for every application.