The problem with ISG is its barrage ability which recharges too fast between barrages. Increasing the barrage recharge time would be a good idea, in my opinion to make it more balanced. It's too effective against brits emplacements at the moment, other than that it's fine considering it's OKW's only option for indirect fire, and not being too expensive, plus the many weaknesses OKW has. (OKW needs a rework in my opinion)
barrage? last i checked (admittedly weeks ago) the barrage was shit. unless i missed something i haven't seen any changes to it either.