After reading so many time that Quad (and/or M36) needs to be OP AA because it the only AA Soviet (and/or the only TD USF ) get stock, I can't really say that I am surprised to see some else using a similar argument.
Those are not the same arguments as OP's, but I'm not surprised to see you saying this
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Counter barrage is mostly fine imo. It's not too oppressive or amazing, it's just right. Can be a bit wonky sometimes, but I don't think it's unfair in either direction
If the lefh feels too good with it to some then I think the ml20 should get a buff. The lefh feels just right the ml20 feels slightly underpowered