This is a tournament!!! We have to fly with weapons from same decades. Realistic and simple if we stay to the rule where opponents use weapons from same decade. We don't have any weapons that can match AIM-120C if we dont use R-77 on Su-27. So the realistic approach is to use AIM-120B vs ER-27 or do early 80s and late 80s where all aircraft get benefits.
For SATAC 2017, 51st chose to mix early and late 80s with two consecutive rounds to win in order to benefit all parts and make it as fair as possible. When I say fair I don't mean balance, I mean weapons from same decade!!!