My DD played 12U A, with regular ASA FP rules; the only rules difference in 12U B was 4 outfielders and bat the whole bench, and that was ok. Nearly all of Metro Atlanta played this way then, and most of them still do. We didn't take away anything else from the 'B' group. Those that excelled played A the next year while some were destined to stay in B. It's ok, some girls don't have the skill to play A. Once past 12U B, all the rest of the B rules mirrors the A.
Taking away stealing on a WP or PB or D3rd is stupid!!! I've seen some 12U B that wouldn't allow the IF to be called and that was stupid, too.