After having one for about 12 years it lost it's air pressure. I sent it off to Mike Gregory and he had it fixed and shipped back to me very quickly.
When Mike installed it I asked him to make the comb height the same as it was with the comb all the way down. I ended up raising the comb about 3/16 of and inch to shoot Trap with.
After shooting one of the best rounds of Sporting Clays I have ever shot I noticed the comb was adjusted up for shooting Trap. Ever since that day the comb is 3/16 of a inch up and it stays there for all my shooting.
I have a G2 stock on my K80 and also my 525 sporting. The recoil reduction is incredible and adjustability of the comb is quick and easy(up down left right). Recoil is less than my Beretta autos. I have never had any problems but I know if I ever do. It will quickly be resolved by Mike Gregory.
I also have a K80 Parcours with a Soft Touch. It also works well. I can recommend either but I am sure you will be happy with whatever you choose.
I have a G-Square on my Beretta 390 Sporting. It has allowed me to still shoot 12 gauge at 76. Best recoil device there is. I have two Gracoils on other guns and there is no comparison. The G-Squared is the best!