MMMM That's the same kinda stuff the guy said that tryed to sell use on cryoing the mower blades.... Watch Modern Marvels on the history chanel...the episode called the worlds sharpist. They did a nice presentation on how freezing metal to 265* below 0 makes metal brittle!
Everyone seems to have their opinion on the Cryoed parts.. Some swear by them.. others don't... Some of the metal guys I've talked to said to warm them back to X temp afterwards...
About like anything else on the internet.. if you don't find the answer you are looking for.. just keep searching.. haha..
It would be interesting to see how long the blades would have lasted if you didn't hit something hard.. Many that use cutter blades for other things swear by them... but they are not hitting hard things with them... or not at the speed a deck blade would...
JDGnut