The difference is that recycle does not require you to keep around (or be given) the untyped in order to then be able to perform the retype. Recycle is also a single syscall, and thus has better performance, than revoke + retype.
Oh yes, sorry, I know the difference in behaviour -- is the difference in performance in today's seL4 similar to what was outlined in the paper? I had it on my list of things to pay attention to based on those results.