One major benefit of this option that may not be immediately apparent is that it lets you turn into someone younger than your current self, effectively curing aging. And any other crippling condition, too.

I'm assuming that since it is specified that one option can only happen once, that the other can happen any time, any amount of times. So unless you REALLY want to go back to one point in the past, just once, this seems like a no-brainer.