I've put many miles on a Shimano Nexus 8 speed with no issues.
My primary bike now has an Alfine 8 and it is really nice (significantly better than the standard Nexus 8, IMO), especially in combination with the superb J-Tek bar end shifter.
The Alfine is smooth, super fast shifting, silent, and offers a terrific gear range. My only gripe is that the step from 5-6 is larger than I'd like, as it is in the "cruising" zone where it would be beneficial to have closer spacing.
Shimano is on the cusp of releasing its much anticipated 11 speed Alfine, which has even better internals and is an oil bath hub like the Rolhoff (easier to service). It also has closer ratios with a bigger step to first gear. Me likey what I see.
I have no direct experience with the other offerings, but understand that they perform quite well.
Last edited by canyoneagle; 09-18-10 at 02:59 PM.