No experience of roads hubs, but i run king hubs on two mountain bikes. I broke a bearing due to operator error when i serviced one of them (service tool incorrectly seated) and the single speed froze at -12 due to lack of servicing (not serviced in 4 years, freehub had water inside) Clearing the water out solved this and there was no damage done to the internals, which i can’t say for any other hubs this has happened too . They are no louder than hope XC’s i use on other bikes, a lot quieter then Pro 2.
Originally, I bought Kings simply because i always wanted a pair and i think they are lovely pieces of kit, but part of the fun for me is servicing them, they are works of art inside. But as has been said, the tool ain’t cheap.
Don’t know whether they would last a life time, does anything? The single speed hub in the same design as other King hubs, and that’s still running smooth despite being ridden only in winter on the Southdowns. It just gets hosed down at the end of the ride and i haven’t replaced anything in it.