Centering bearings and technique are barely related, in my opinion. All the technique in the world has no chance of fighting precessing that is caused by flat bearings. It’s just physics.
There is also no such thing as a throw that will guarantee the string will be in the middle of a flat bearing. If you prefer to keep the string from touching the walls or response area, a centering bearing will accomplish this.
If it was all about technique, most of the pros would just use flat bearings. But they don’t. The majority of the pros out there are using profiled bearings; either KK or CT(x). Majority doesn’t mean “all”, so of course you will find examples of amazing players doing just fine with flat. That’s not my point. My point is that profiled bearings are not simply a crutch to compensate for ‘bad technique’.
I can’t feel a difference in the ways some people claim. “Oh, the profiled ones bunch up more” (I tested all evening once and found this to be BS, at least for the tricks I do) or “Flat bearings give a nicer bind” (also turned out to be BS).
However, profiled bearings DO help with precession and tilt. And no matter what the profile is, the build quality of KK and NSK bearings “works” for me. Ditto for the build quality of OD 10-balls, actually, it’s just that I hate how I’ve had a screeching period in every single one. Drives me nuts.
Regarding 10- vs 8-balls, there is probably a reason based in physics for 10-balls to be generally quieter, but it’s not a rule. My NSK bearings have 8 balls and they are way quieter than any 10-ball I’ve ever tried, including the OD 10-ball. I believe the tolerances have more to do with it than the bearing count, and OD 10-balls probably also have fairly high machining tolerances. (side note: interesting term! Counter-intuitive to me, since what it means is that deviations are NOT tolerated… semantically, I would think there should be LOW tolerance in a high-quality bearing… but that’s not how the term is actually used!)