Recently I played a few casinos where they had a rule against switching to multiple hands. If you started with two or three hands, fine, but if you started with one hand you had to stick with one hand. Seems like some casinos are wising up to playing multiple hands in positive counts.
I've tried playing from the start with two hands, but before you hit a positive count, it can be disastrous. I haven't simmed it, but instinct tells me its not the way to go (someone please verify). If you can wong in, that's the time to play two or three hands, but be ready to leave Dodge quickly after the positive run is done.