I'm afraid I can't add much on the technicalities of the 7.62NATO vs. .308 WIN, except to point to some relevant web articles.
With regard to shooting milsurp through your accurized semi or bolt-gun.. I don't see a big problem with this, as long as the shortcomings are understood.
Most of my friends who shoot medium range (200-600) with 308 semis try to find one batch of milsurp ammo that works well
in their rifle (both accuracy and reliability), and then lay in a pretty big supply of it.
Even in bolt-guns, using milsurp ammo can make sense for certain types of practice. Consider that a "good" batch of milsurp can put 20 rounds into 1" at 100 yards, throwing maybe 1 or 2 out of that group. That is certainly good enough for that "medium range" practice at 200-600 yards on practical-size targets (say 2-3 MOA). There is a lot that can be learned without "1/2 MOA" ammo.
In my AI-AW, I have a shot a ton of the Australian F4 surplus. I don't see any pressure problems and the recoil is milder than my normal 155 Scenar loads. It tracks my normal dope out to maybe 500 yards, but needs increased elevation from there on out. I don't recommend it for shooting beyond 600-700 because it has poor L.R. performance.
My shooting partner has shot a lot of the South African surplus in his Surgeon .308. At 100 yards, it shoots like this:
(I think he said he pulled the right-hand shot, and the high one had more recoil than the others.)
Hope this helps...
-z