I haven't used the new (AWC) hubs but can say that their S3C hubs are crap.
The primary problems with the S3C hubs relate to the clutch/driver assembly. They have a tendency to lock up going into third because the clutch gets caught between the pins and the ramps on the planet cage that are there to make it so the clutch will ramp off the planet assembly when you back pedel in 3rd.
On mine I've also had problems with the brake not engaging while in 3rd, but I haven't figured out why this happens yet.
To be fair to Sturmey, the AWC hubs have a differently-designed clutch. Specifically it looks like the design changes are to fix the problem with it locking against the pins while atop the ramps. And I've not heard the same complaints out of AWC owners as from S3C owners (if only I'd listened to them. :<) The AWC hub has been around for long enough that if it was a lemon it'd have a bad reputation, yet it doesn't, so I'd guess from that that it works ok.