Say Gai died and was brought back with Edo Tensei. Could he used the 8th Gate Of DEATH, with no drawback? Since he's Edo he wouldn't die...so what do you think would happen?
Probably not. I expect he would need to take some time to regenerate afterwards depending on how destructive the 8th Gate is on his physical body, but then he'd be able to use it again.
Nope, that's like saying Itachi would suffer from eye pains & blindness after using the MS, note that izanami is a kenjutsu that seals away the eye & doesnt make it go blind.