After I got killed lots of times by it recenlty, I decided to go back to it and stop using the STG44.
It turns out that the M2 can function almost as well as a good SMG in close quarters and can still have a better reach than smgs.
I use it with quick aim, enchanced grips, polished action and lightened stock. I am not sure about the right sights for it though. x1 seems a bit too little so right now I am trying x3