mr1911
I have used one and I do not recommend them. While they do work, they do have their own issues. First, they do require some fitting to get the link in the right position for the spring to act on properly. Second the leaf spring being part of the spring guide tends to dig into the link over time, which means that links need to be replaced.
If you are considering a group gripper, I would suggest that you do two things instead. First, have a gunsmith check and replace the link in your barrel with one that is the proper size for your pistol if necessary. Second, install an oversize bushing and a full length guide rod. The bushing will hold the muzzle of the barrel in the proper position, and the guide rod will support the recoil spring on its full length and will make the slide action more consistent, which will make your pistols mechanical accuracy more consistent. In addition, the guide rod will counteract some of the torque in the barrel caused by the bullet passing through it, which also helps the pistol's mechanical accuracy to be more consistent.