Renting DVC points can be a great deal, depending on price per point and how many you need. Keep in mind if your renting points and FD gets offered you have to pay for dining.
You can't combine discounts so it is either FD or Room only discount and not both.
You need to crunch numbers and decide what works out better for you.
Generally speaking if you are staying at a value resort FD works better than the % off code. Moderate is kind of a toss up and Deluxe the % off is better.
Hope that helps