ORIGINAL: aa2dd
Ceramic bearings are okay I guess, but if you dink the engine, chances are good that the bearings will be damaged. I replaced bearings in my Saito 100 with ceramic, and it ran just fine till I had a mishap with the ground! It was not a hard crash and did not do any damage to the plane to speak of, BUT, it trashed the bearings. the ceramic balls chipped, busted or what ever you wnat to call it. I figgered that i spent approx 90 bux for nothing but trouble.
Obviously you didn't buy your bearings from RC-Bearings.com. Pauls prices are (from memory) much more reasonable than that.
Personally I don't bother with ceramics for sport engines -- just plain old bearing-steel ones work fine and I haven't had to replace a set of Pauls yet, they seem to last much better than the factory originals.