According to the literature that came with Founders Club you can upgrade in Aruba. You can't, however, use your free week in Aruba, but you can use it in any of their resorts. I have taken advantage of this and I think it is great. You go to any of their other resorts without having to pay a maintenance fee. You also get a week deposited into RCI. If you can use it fine. I think it is a great deal. Show me another company that does any of this!
I too have became a founder's club member last year on two of my contracts and again this year on two more. At first I was annoyed about not being able to use the free week in Aruba but I now realize, its free!
The RCI deposited week has been great. I deposit the weeks they give me and I put them together an get a really great resort, back in Aruba, for free. Its doesn't have to be Occidenal.
I believve we get a discount on the all inclusive too but since I don't use it, I'm not sure.
Enjoy it! We're lost enough benefits over the last 2 years that I take whatever I can get from them.