If you have a gun that fits you properly...will the addition of a well formed cheek piece further mitigate felt recoil?

If the gun has a sharp comb that hits your face every shot, the addition of more facial contact(cheek piece) may help. If the gun fits properly, and doesnt raise into your face as a proper fitting gun should, a cheekpiece wont aid in reducing any noticable felt recoil in my opinion.

If the rifle fits you properly I do not think it makes any difference.

I have shot a lot of rifles with a cheek piece, yet my 450 No2, 450/400 and 9,3x74R do not have a cheek piece.

Truely if I was blindfolded I do not think I could tell when I shot a rifle if it had a cheek piece or not.

However, I could tell if it fit me or not.

As a lefty, I've acquired/fired any number of heavy and medium caliber doubles and bolt guns that have a cheekpiece on the wrong side. Never had a problem with recoil as long as I mounted them firmly with the cheek well onto the stock.

Regards

If you're getting hit in the cheek upon recoil, your stock is too short or has too much drop. You should be able to mount the gun with a solid cheek weld, so your whole upper body, head, and gun, move as one unit upon recoil.
If you can't line up the sights with your cheek tight against the comb, then a cheek pad to raise the comb might help.
If you have the soft part of your cheek below the cheek bone against the stock, without contact of the cheekbone, you're going to get hit.
Hope this helps, ND