I don't think there are any, just like for other diets. It's very difficult to get statistics for these sort of things.
I did come across some independent research the other day that said those that do a VLCD are more likely to keep the weight off. It's possible, but I dunno.
The problem isn't whether you keep the weight off after CD, WW, SW or any of the others, it's whether you make the lifestyle changes that are needed after the diet is over. Doesn't seem to matter which diet got you to that point in the first place.