I have a bunch of Sprinco reduceres in my guns. I would say around 15 of them. They do work much better in some guns than in others.
Funny the poster who mentioned the Beretta, the one gun that I could not really tell any difference in was a Beretta, BUT I was not shooting full power factory ammo either, it was reloads. I have noticed that they seem to work especially well in SIG's (the SIG P225 is as light shooting as an H&K P7) and the Glock 30. If you get one I have a couple of suggestions. Use full power factory ammo and do not limp wrist the pistol trying to feel the effects, the tighter you hold the pistol the better the system works.
The units do not reduce recoil. What happens is that the recoil pulse is spread out over a longer period of time. That reduces the felt recoil.
They also save wear and tear on a gun, especially a 1911. Back in the 1980's when I started shooting IPSC shooters were putting heavy springs in the 1911 to try to reduce recoil. This causes the slide to slam into battery and was causing frame cracks around the slide stop hole. With a Sprinco reducer you use a lighter than normal recoil spring, enough force to get the slide back and the barrel to lock, because the sub-spring slows the slide down before impact. So you save impact going both directions. Sometimes the mainspring is too light. I ran into this on my Browning HP's in 9mm. My barrels are tightly fitted and the Sprinco spring was not strong enough to return the slide to battery, so I use the spring for the .40 cal HP in both the 9mm and .40 S&W guns.
I have not had any functional problems with the systems other than the HP spring change. I have had some fit problems with a couple and the problems were immediately corrected by the company. Sprinco has a great offer that I urge you to take them up on so you can decide for yourself. You can buy a unit and try it for 30 days. If you don't like it send it back for a full refund.
sensop is using one in his Commander and is quite happy with it last I heard. I suggest that you contact him for an opinion.