John Baker: I've always wondered also - being just a casual Reversi player (far from being an expert or anything).
Personally, if I can - I try NOT to start with a diagonal start position if possible - just since in the back of my mind, I know most "experts" probable play that game that way - and doing that might "mess" them up some. Of course it does not work and I still lose - but O'well - worth the try.