Here’s my experience, and keep in mind this is a test group of exactly 2 guns, so not a significantly sized test group. Take it for what it’s worth. Several years ago I tried the Sprinco recoil reducer guide rod in both my Sig P6 and a '94 P220.45 (the old pressed/folded slide model, not the newer type). All proper maintenance parts had been replaced recently at that time, so I eliminated as many variables as I could.
What I found was maybe a very minimal percentage decrease in felt recoil. It was so minimal, in fact, I don’t know whether overall recoil was even reduced, or if it was more a matter of changing the recoil impulse in such a manner that the recoil impulse was slower (They’re effectively a variable spring rate due to the multiple springs of different sizes). The extreme downside is I found that, at least in my 2 different models, neither gun would feed a majority of JHP’s I put through them. I don’t know this for a fact but, it appeared that the last little bit of slide travel (before the breech face picks up the new round) was attenuated, and possibly overall slide travel reduced due to the increased tension from the springs at the end of slide travel rearward. Bottom line, I experienced a significant number of Fail To Feed failures with a number of different JHP’s:
-Black Hills 230gr and 147gr JHP’s
-Speer Gold Dot 230gr, 115gr and 147gr
-Winchester Ranger SXT 230gr and 147gr
-Corbon SD JHP 230gr and 125gr
-Federal Hydrashok 230gr and 115gr
The FTF’s were also pretty significant upon reloading, regardless of using the slide release or the overhand method.
There were a few others I think. I actually wasted a good amount of ammo testing these out as I had significantly more disposable income at the time. 
About the only ones I could get to feed consistently were Corbon Pow’RBalls. Switching back to a new stock recoil spring and guide rod, and there were NO feeding problems with any of the above listed rounds.
Bottom line, for duty usage, I would say these are a NO GO. I know Alan, the owner of Sprinco (as an acquaintance), and he is a really nice guy. His guide rods are very well built. I just can’t recommend them, with at least the P220 or P6, for duty usage.