Has anyone used oil bath hubs on a TT?

I never really looked into oil hubs because of too many other things. I like the idea and they are not pricey. It looks like 2 new seals cost more than the whole kit. So the question would seem to be how many miles does the seal last and how often would we still want to replace the seal during bearing inspections.

I didn't notice if they said how many miles to run them before an inspection. How long would you run them? When I was working our highway truck department ran them on medium and heavy trucks but I dont know what interval they serviced them. They usually ran stuff until it failed. Duuuhhhh