I installed the Wilson Shock Shield Hybrid a couple of month ago and love it. Yes it adds weight which I like.
Weight of WSSH installed (cut): 0.84 ounces = 23.7 grams
Weight of my old grip installed (cut): 0.51 ounces = 14.4 grams
Estimated weight added: 0.33 ounces = 9.3 grams
So basically 1/3 of an ounce added which also made my racquet more headlight and that's much appreciated. The installation was slow but I did a good job the second time I did it (threw the first one out because I did a bad job). I've been quite pleased with the feel that I'll install another WSSH on another racquet tonight or tomorrow.