Bearing SIZE is the predominant determinator of speed potential - any bearing catalog clearly shows that relationship.
When you start reaching the speed limitor, then internal mods start to gets tweaked to enhance life at the high speed (IE
lastic cages versus riveted cage, special tolerance balls,etc). Special lubes also help. Mounting accuracy helps more that anything else.
Interstingly, "bettter bearings" (as in ABEC 7 vs ABEC 1) do more for running accuracy than they do for high speed operation potential. However, at speeds approaching the bearing size limitation, ANYTHING you do to improve operating accuracy helps the situation. BUT, when it comes to life calcuations, I don't recall ABEC specs being a factor in the life calc process.