Yes, you can use RCI to trade into DVC, we've done it three times. (Once at Beach Club right after they joined RCI, and twice at Saratoga) My parents also have a fixed week (referred to as "RCI Weeks") rather than Points. Unfortunately, the trading value of my parents' week on Cape Cod has been holding steady or slightly declining while the trading power required to get into DVC has been rising steadily, so we're getting to the point where we are either being priced out of the trade, or we would have to combine two years' of deposits to have enough trading power.
There are also a couple other issues. Disney has been only depositing 1-bedroom units for a few years now. Three or four years ago we got a 2-bedroom at SSR, but that was one of the last they deposited. Last year we only got a 1-bedroom.
And since DVC is in high demand in RCI, you need to start an Ongoing Search VERY far in advance (like 9 months or more) and give them a large window of dates you'd accept. We always gave a 3-4 week window where we'd accept any check-in within it. And don't expect the match to come more than 4-5 months out. (The waiting can be nerve-wracking)
Lastly, Disney has doubled their "incoming DVC exchange fee" from $95 to $190. (They did this so they could offer free exchanges by DVC owners into RCI) All of the fees combined (The DVC fee, the RCI Exchange fee plus the annual dues for the actual timeshare) is putting it to the point of being cheaper for us to just rent DVC points.
-Rob