I do have a set of cheap Performance sealed bearing hubs. They've been used mostly for commuting off and on over the last 15 years and they still feel super smooth. 3-5 years is probably a low estimate even for someone who puts lots of miles on their wheels. The good thing about the cartridges is that when they go bad, they won't damage any other part of the hub. If you ignore a servicable hub long enough for the bearings to get pitted, it will pit the bearing surface of the hub body, and then the whole hub needs to be replaced.