i think your urethane helps alot more than bearings most of the time. I ridden abec 5s for as long as i can remember and they are just as fast as any abec 9 if you put gas in them, rinse and then put 3 in 1 back in.. they are smoother too.
Good wheels to have are really old hard b model 5 spokes, drives, metalcores, stock 14 spokes, and yaks if in front.