Their size is different and as such they play differently. I suggest just trying both out to really understand how each feels on the string.
Large bearings spin longger than smaller bearings
That might be true, to an extend.
However, since small bearings have a smaller diameter (duh) they have more wraps of string around them when they are would up. > more rpm out of your throw
For me, my SB yoyos have plenty of spin time.
You seem to be mistaken. The Buddha King 2 which holds the world record for sleep time has a Size A bearing in it.
Yeah, they both have a different feel to them. The small bearing also tends to snag more than the large bearing. I like large bearings better.
small bearings tend to have longer spin times but not longer on string tricks as the large bearing because large bearings have larger gaps
small bearings sleep longer on just a sleeper. if you do tricks that require string wraps, they slow down faster though, that is why most bearings are all c sized.