When I used to fly r/c helicopters, the quality bearing was important due to harmonic vibration. Quality helis had as much as 16 or more bearings in them The smoothest bearing by far were german bearings and I mean by far even over Jap ones which were next in smoothness, the USA, then of course Chinese. I would put my finger in the race and turn slowly and you could feel the slightest problem. The german ones were so smooth, you had to look to tell you had bearing on your finger.