I think most SA units are deposited with RCI. In which case, it's a TPU or 'trading power units' system, essentially another points system.
So, depending on the amount of TPUs you have, any RCI timeshare is available to you. I don't believe many of the SA t/s's have a value over 20 TPU or so normally, so you'd have to combine with another unit (or more) to afford some of the nicer resorts. It can still be a good value depending on the current exchange rate when you pay your levies--and/or if you look for RCI specials or shoulder seasons.