You left out the other part, which I think is significant: ... though they can also choose to keep the battery and pony up the difference between the pr

You left out the other part, which I think is significant: ... though they can also choose to keep the battery and pony up the difference between the price between of the old and new batteries. It's hard to say how much of an issue that is going to be without knowing the typical prices. Also, it needs to be balanced against the fact that a typical supercharger recharge is free.