FWIW I've had great experience with the Acer ceramics. They have the non-contact rubber seals- the best of both worlds. Compared to "standard" steel bearings they have about 5x less friction per a "spin test" with my tires. I have my Rustler outfitted all the way through with them and it might as well be MagLev it rolls so smoothly...
I can't speak on longevity since I haven't had one fail on me yet.
