I really hope we can save during endurance races. The save back up is a huge buffer for that, I will always back up before and after an enduro or B Spec binge but still, saving during a race is so convenient and smart.
I was hoping they will PSNID-lock them.
This way it opens the Pandora's Box of 100% save files for interwebs usage.
I kind of feel your worry a bit but every other GT game to my knowledge had the 100% frenzy online and it never bothered me. Perhaps since I was never playing online in those games it masked it.
I look forward to being able to look at an online profile, see that they are clearly a 100% save file cheater, and the proceeding to smoke the shit out of them in a race because they never put the seat time in