Just my $.02 worth. I shortened my draw a bit when I switched to lefty. I think I may have opened my stance a bit?
Whatever, I was drawing 29" right handed and now draw 28" lefty. I just picked up a 50# KMag lefty. I can shoot it reasonably well, which pretty much sums up my shooting with my longer bows too. I hate to think about adding another 1" of draw to that KMag, though. I don't know if I would hit a solid wall, but it sure is getting stiff at 28". If I ran into someone with a 45# KMag lefty that wanted to move up a bit, I'd trade in a heartbeat, or New York minute - whicher is shorter.
Having said that, I had a 54" Super Necadah 45# right-hander that drew smooth as butter all the way back to 29".