I don't have actual experience to know if this is true, but it did come straight from an RCI manager on the January Member Cruise...
Although
DVC members can only see about 500 properties on the web site, if there is another RCI property that a member desperately wants to go to, they will supposedly work with the member to try to make it happen, "based on availability, of course." This would almost certainly be a major, major trade down as the ones that we have easy access to are supposedly their best properties, but hey, if someone wants to spend their points on it...
During the RCI presentation on the cruise, I got the feeling that RCI is pretty desperate to get people to trade their DVC points to them. The managers giving the presentation seemed to be extremely helpful. I just wish they would show the RCI "Signature Selections" properties on the web site, but when I asked about that, they indicated that there are no plans to show them there in the future.