T400s fail too, just like every transmission can. Their biggest advantage is they have an aftermarket SFI certified case. So if they do have an internal failure, it will help contain the explosion. Being that the 727 we are discussing has a bolt in sprag and billet front drum, the main explosion risk is already addressed. He is simply asking about upgrading to hardened shafts. At his power level, and intended use, the stock shafts should be fine, but if he upgraded, he will never need to worry about it again.