No, a Decelerator doesn't work like a brake for every kind of recoil problem people encounter. My wife has Decelerators (or another variety of soft pad) on every one of her hunting rifles, and they didn't help at all with the recoil headaches she started getting a few years ago.
By trial and error she found out more than about 15 foot-pounds of recoil resulted in the headaches, regardless of the recoil pad--or stock shape, or whatever other factor Campfire experts come up with then discussing recoil. She did fine when killing a cow elk this year with her .257 Roberts, but would like to be able to use her custom .308 Winchester (with a stock made to precisely fit her) for bigger game. We tried reduced loads with 130-grain TSX's, but by the time we got them going slow enough to prevent the headaches, there was no real point, since her .257 worked just as well.
So she's going to have a brake installed, and since she has probably 3 pairs of electronic muffs that will work I doubt she'll have any problem.
