Right wing, left wing it is all in the archers mind. For me the only thing I noticed was less feather wear, but there are another bunch of reasons for feather wear and I may have fixed the wear problem by accident.
I have also read somewhere that the left wing feather is less likely to end up in you bow hand if you have a loose quill. I do not plan on trying that out on myself.
OK, so as for performance goes I have read it will affect the single bevel broad heads that have a right or left bevel.