-- Last Updated: Dec-12-12 5:23 PM EST --
I really think it's a personal preference thing. Coming from a road bicycle background; side to side flex in a bike frame is a bad thing. Energy that should be devoted to forward motion is lost. Fore and aft flex absorbs road shock and less forward energy is lost. I ain't no fizzicyst but when your paddle flexes forward and back, very little energy is lost. If it feels good, enjoy it.