I like to advance my Biopace rings by one hole. Lots of folks did that back in the day. Biopace only gives you 5 different ring orientations, while Rotors give you, umm lots more.

I don't mind Biopace on larger rings but it was kinda kooky on MTB cranks, I'd always swap out my little ring for rounds.

Sheldon Brown claimed to have run Biopace fixed gear, so they don't take up differing amounts of chain at different points in the stroke.