Hi Chris
As many have already said, caged bearings in this application are just a no no because the cage cant handle it for long and would fail without warning and fast. Since the cage is what keeps the whole inner race central, when it fails its catastrophic and sudden stop to put it mildly.
Unforthnately there are alot of cheap full complement ceramic 608s but most are not good due to poor design or build or both (for this application), few are of okay design but consistency in quality control is poor therefore you can get a good one some times and other times is worse than a good SKF steel 608.
So I believe the question you need to ask yourself is are you prepared to put your engine on the line for someone else poor design or build quality in manufacturing bearings that at best will be okay for a skateboard ??