Releasing the F2G conceptual plane, broke late war prop BR and as long as this thing remains in this game/gamemode, it will be fuel for never ending debates. Bringing it up to 7.0 would at least make 5.7 more playable again. But in my opinion it should be completely removed from realistic and simulator battles.
Or add a mode without BR where planes from their actual time have clashed. Like that we could still keep battlerating + have this as a feature.