Cryo is not worth the money IMHO.
X2. JBs right on the money. Cryo does
absolutly nothing for de-stressing or the durability. It can ruin it though by warping it during the process (if you want to pull a bad joke on someone you dislike).
If going this route, I only recommend Metalax. I researched this and cryo for many years in the tool industry on Husky stack molds I built. There's no substitute and was the only thing shown to truly de-stress metals with out warp or compromise of the integrity of high stress components. There service life in most cases was doubled or more (service life after was about 5-6 MILLON cycles at 700-900 tons of pressure).