I bought a Sprinco Recoil system for my Beretta 92. It works great. I hear it is the closest thing to the HK system also. As Stephen noted, the graduated spring makes it hard to rack back the slide for the last inch or so. But there definitely is a difference in recoil as the sight come back to the target a lot faster.
You're gettin' ready to blow? I'm a mushroom-cloud-layin' motherf**ker, motherf**ker! Every time my fingers touch brain I'm "SUPERFLY T.N.T," I'm the "GUNS OF NAVARONE."