I feel it would be better to decrease Bren gun cost from 45 to like 35-40 munitions to improve how quickly they scale, rather than increasing how much they scale.
These types of changes result in powercreep. Mid/lategame Tommies don't have a problem against Ostheer infantry, but only struggle against some OKW elites. With such a change I see Grenadiers requiring a buff in a followup patch (also because of the Riflemen near accuracy change) and thus the cycle of buffs continues.
I like the concept, thought I’d like to see Brens nerfed a but if they’re cheaper. That way they’re more accessible early, improving the early game, and less lethal in the late game where they already excel at.