The main reason I purchased the HGVC in addition to the Marriott was to try the points trading system, and I was able to get 5,000 points for $7,000, which I think is a pretty good deal, considering that Hilton is selling the same rooms at a newer resort in Orlando for over $20K.
I've never traded my unit through RCI, but I'm told that you exchange 4,800 HGVC points for a red 2 bedroom. When I asked the resort management what kind of trading power that gets you in RCI, they said that since HGVC offers usch high quality, the trading power is high. Of course, that's from the horse's mouth, so take it with some salt.
Bottom line, I think a purchase at a HGVC resort in Orlando is one of the best deals around. You might also consider Sheraton Vistana Villages, which offers a similar points trading system, and the Starwood Vacation Network offers more resorts to trade into. It will be a few more years for Hilton to add some more choice.
Good luck,
Mike