Don't forget, cortisol, although not vital to life, is a very important hormone for recovery from stress. Without sufficient cortisol, you and I wouldn't be able to cope with physical or mental stresses without having major illnesses.

If you want to reduce cortisol levels in order to reduce post workout soreness that's fine...but don't take it to stop all cortisone production...that wouldn't be healthy.
I think a better way to decrease cortisol's destructive results on muscle tissue is to take alpha lipoic acid at some point after your workouts. It will decrease the total recovery effort by your muscles and thus will allow for more gains to be made in a much more efficient manner (less time and less energy required).