I would like to remove a 4 gang steel box that is pretty shallow. I would replace it with an old work PVC box that is deeper. I would like to add 2 smart switches replacing existing switches on left and right side of the box. I think there are too many wires in there to add the smart switches in that shallow box. My question is how much work will it be to get the existing box out? I see the metal bracket on the left side of the box which apparently connects to the face of the stud on that side. There is a large screw in the middle of the right hand bay which I don't know what it does. Looks like it might be clamping something to the back of the box. The studs are 2X4's and it appears that nothing is behind the steel box. So I'd like to replace with a PVC 4 gang old work box that is a good inch deeper. The house was built in early '80s and I believe the steel box is original.

I had this dimmer installed last week, when sliding the slider up and down its clicky at times....it doesn’t affect the function though...normal? I was charged a fair bit by a professional to install this so hoping he did it right.