from br 12.7 the chances to join a br 13.3 match are high and common, players are complaining all time about su30 permiuns, even if su 30 is not the best 13.3 br plane its spammed because its premiun and everybody buy it.
the main problem with this its armament gap fox 3 vs fox 1, but trust me this cannot be fixed, its normal to have a step from fox 1 to fox 3, if is not the su30 will be another plane even some 13.0 planes have fox 3, but i think ok we cannot deal in a br 12.7 in long range vs fox 3 spammers so the answer if to close them but suprise even at close distance there is no option most 12.7 planes dont have fox 2+irccm (every class of f18/mig29/etc) so no chances at long or close distance.
this its stupid a lot of br 12.3 have fox 2 with irccm, fox 2 with irccm should be standar at br 12.7 f18 and mig 29 are capable to carry fox 2 with irccm and should get it in game too.