i'm surprised your split sole ballets give you balance trouble.
i swear by them and won't wear anything else.
perhaps the brand or style you have has too thick a sole/heel pad in comparison to the rest of the bottom, making the surface uneven.
these are the ones i have worn for many years [ model pro #1c ]
http://www.sansha.com/footwear-soft-canvas.html#
i like them much better than an open shoe b/c stuff [glass, restaurant yuck, little pebbles, broken beads from our own costumes ] can get in the open shoes very easily and that is what we are trying to prevent.
good luck and happy dancing!