Da Big Thinker, personally, I don't think, that Winny is universal solution. I read good amount of posts from guys who used Winny and still got gyno, either from Fina or Deca.
Most likely, it does work for most of the users, but, perheps, not for everyone.
As for Fina gyno, because of short ester, simply stopping in time should prevent any problems, and our little discussion is really more theorethical then for practical applications.