There is no real downside or penalty for changing resorts if available.
There is one issue to be careful of here....if you switch a reservation which will require fewer points and are within 30 days, the "extra" points will have to go into a holding account. If the same thing happens more than 30 days before, there is no problem- the extra points will just be returned to your account and may be banked (subject to regular banking deadlines).
Enjoy!