I'm using 600 hubs on my roadie, they run nicely. According to one rider, much better than his new Ultegra. Some dude asked me to race him (friend in friendly comp). I did and smoked him by 10 minutes on a 10 mile stretch. When he arrived, he said it was that his newly built wheels were slow rollers due to the Ultegra hubs.

We both use Velcocity Deep V rims (28) but my hubs are 15 years old. What I gather from his comments, the new Ultgra hubs are heavy slow rollers compared to my 600's.