Wow.  I have no interest in this game at all.  Sorry Fencer (et.al.)  Other than being played on the same board, this game bears no resemblance to backgammon at all.

I think LionsLair has a great idea for a variant.  (I don't think you should limit doubles though).  This would make for an interesting game.  I think that instead of limiting doubles  you could do something else to benefit your opponent when you choose to play doubles.  (Perhaps your opponent would automatically get a doubles option on the remaining dice).