Another fix that's been suggested before that Iv found might work would be bumping Volks up to costing 255 MP and making them the middle ground between riflemen and gren's giving OKW a bit better early game but giving them more of a MP drain.
Currently in 1's and 2's the Kubel can often be a liability due to the reduced capping power you have early game, personally I would find it better if the Kubel and MG34 were swapped.
