When you put it this way, it makes me realize I'd rather live 400 years while losing three quarters of my waking hours than to live 100 years without any loss of waking hours. Experience centuries, and all that.
Exactly. And just imagine they find fixes for all the age related diseases (basically any organ failure) in the next decades, but not for Alzheimer‘s. You will hate yourself for not just having slept more. Perhaps everybody is then almost guaranteed to turn 125, and you come down with Alzheimer‘s at age 65.