Like Dean, I am more a fan of II than RCI. My non-DVC timeshare is dual affiliated but II just has much better options (just not DVC, but that's why I own a DVC.)
Resale DVC contracts cost tens of thousands of dollars with high annual dues (points for a 1BR for a week start around $1400 per year). My non-DVC timeshare cost $1 on ebay and the annual dues for a week in a 1BR cost around $400 per year. I have traded that $1 timeshare for some really nice Marriott resorts (in II) in Southern California, Kauai, St Kitts, Vegas and Hilton Head.
I like being able to trade my Chevy for a Lexus, as Dean put it. If you trade DVC in RCI, most of the resorts would be a step down from DVC in quality (except for the Hiltons in Hawaii and a few other exceptions if they are available), and obviously those timeshares would cost less upfront and have lower annual dues.
You would have similar access to trading for RCI resorts with some $1 timeshares from ebay as with DVC - buying DVC to trade in RCI just sets money on fire. So if RCI sounds appealing, do your research on TUG and see if a $1 timeshare might be a better option for those trades (or just use cash). But just buy enough DVC to use for DVC resorts.