I've only ridden my new 404s once.. but they hubs are noticably better than the hubs on my Mavic Ksyrium Elites. I can't speak in regards to long-term usage.

mike

Zipp has had a lot of problems with their hubs over the years. It seems like these problem stopped with their 2002 models. I spoke with a Zipp sales guy last year and they had yet to have a hub return with the new hub.

I have a 2000 404 and the hub is fine, but I use it only in races. I wouldn't have confidence in the hub to put lots of training miles on it, but I don't want to do that anyway. It is a race wheel.

I still hear that the American Classic version of the 303 and the 404 is still superior to the Zipp offering. http://www.amclassic.com/

I have the newer 404 Zipp Hubs and have had no problems. My training partner had the older ones (they have a gray strip in the middle). His bike box got banged around on the way to IM Florida and the hubs were offcenter and rubbing. The old design made it easy for them to get off center. The Zipp rep on site totally rebuilt them on the Friday morning before the race - he was great.

So, if you are buying new ones, you should be fine, beware of older used ones.