like i said above, banked/borrowed pts are like any other pts in that you can use them to make a reservation that can be rented out.
but you can only move pts ahead one UY, so that can make things tough on every-other-year travel (and worse on every-third-year plans).
one other thing to keep in mind is that you can transfer
current UY pts to another
DVC owner.
banked/borrowed pts can be used to make a reservation that can be rented, but they
cannot be transferred to another owner.
(also, DVC prohibits accepting money for points transfers...but some people do that anyway...just be aware that disney won't get involved in a dispute and member services might get angry if you suggest that money is trading hands in a point transfer.)