Are you trying to decide between buying C+ and F?
I'm 6'5" and I can say this much, you won't die in C+. Is it comfortable? I guess that's really a matter of your own personal preferences.
FWIW, I sat in regular non-comfort main cabin for three hours a couple of days ago after doing a same-day confirmed change away from a flight where I had a confirmed F upgrade and I survived. Even managed to get my laptop out and do some work.