Re: 12X for 750 yards
In my experiance, for hunting even a 10x is decent for 750 yards. Much after that I like more. I like more anyway but I find 10 is at least adequete. BTW, I have shot all my personal best groups at 1K with a fixed 10x. Dont know if that has anything to do with it but it is an interesting point.
Long range shooting is a process that ends with a result. Once you start to focus on the result (where the shot goes, how big the group is, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.