I put a lot of pressure on the comb because without doing so I lift my head often. The PFS comb does not recoil or move back when the stock compresses. The RAD and Gracoil both allow the comb to recoil back with the gun. I find the RAD and Gracoil more troublesome and uncomfortable than the PFS.
You may not have the butt angle adjusted properly if the comb comes up to your face when you shoot. Try changing the angle of the butt by adding a spacer under the top of the butt pad.
Fit is the answer here. The PFS (I have two with the "Universal fit" comb-- and I do put a lot of cheek pressure on the comb),is the only real answer to your problem. It has the best adjustability and the best recoil reduction. You probably need someone to help you adjust the entire stock to you. Don't be afraid to make changes and experiment...if you are going to continue to shoot, it will be with a PFS.
I have a PFS with the Ultimate comb system, I didn't like the contour of the factory comb so I had one shaped to fit my face so it locates directly under my cheekbone/eye and keeps it there.
Experimentation is all about fitting your needs. A good gun fitter will speed up the process. A call to Vern Brown at PFS is always worthwhile. Depending on where you live, you may be able to meet up with Vern for a fitting.
With regards to your back surgery, I had a double fusion 6 weeks ago. On Thanksgiving morning I took the dogs out and carried my SxS. I shot several Pheasant ans Quail and had no discomfort in my back AT ALL. I would like to know waht problems you were having after such a long time since your surgery.