Whether the recoil reduction is "worth" the cost and installation of the mercury reduction device is up to YOU. If you shoot a lot of rounds from powerful recoiling rifles from a benchrest, and the kick bothers you, then yes, it's "worth it".
The mercury recoil reduction unit works because it not only adds weight to the gun, but the liquid mercury has inertia, causing it to remain momentarily stationary, and when it does move, it distributes the recoil sensation over a fraction of a second. The recoil becomes a softer "push" and not a "jab".
HTH
John