I regularly shoot with an Army Reserve Shooter at XTC matches. His team shoots at Perry every year. He says they are using the 77 SMK all the way out to 600 yards because it works, whatever windage difference between the 80's and the 77 is insignificant, and it makes the logisitics simple.
I still have boxes of 80's, so that is what I will continue to use till they are gone.
It may be a while, I am having more fun shooting vintage bolt rifles in 308 XTC, or my M1a.
I got my Distinguished with an M1a and I don't feel like I have to prove anything any more.