You are only allowed 1 transfer (in *or* out, not both) per use year per contract. With renting, someone else controls the points, reservation, dining plan, and DME. When you have points transferred in, you control them. So, you can bank them (if eligible), change your reservation, decide on a dining plan at the last minute, set your own DME. Basically, you don't have to stress that someone else controls your vacation. Use year can get a bit tricky, though.