It works for spins whenever it's surfable, you just have to be able to do them!
ie. because it's a flushy feature you have to do them quite correctly otherwise you'll flush, not like holes where you inevitably spin just by edging a bit.
To answer the question Peter put up at the start, it's never really retentive.
Stackallen is perfect for absolutely nailing Surf, spins etc. If you don't do something right it'll tell you, but probably won't punish you with a capsize.
If you want a level, look up when the first(I think) freestyle training day was last year and that was towards the higher end of the range. Probably easier to just ask someone like Ronnie.
Also, Sluice. I like Sluice, we should go there too...hopefully it'll start working soon.
(and none of your anti-sluice dogma Peter, you haven't surfed it at a decent level and your Weils non-sense isn't supported by statistics)
I like Stackallen, it's probably working at the moment, let's go there...Sunday?