There are times when RCI works well, and they are times when a private exchange works better.
For instance, if (like the OP) you have a desirable timeshare to trade, and the timeshare that you want to trade into never gets deposited in RCI - a private exchange is likely to be more successful.
If however, you have a timeshare worth a lot of points, and you want to use it for exchanges into resorts that are plentiful on RCI, then RCI is the way to go.
One size does not fit all...