I have not used the Extreme Limbsaver system, but I did use the NV system on a few bows. I really think their effectiveness depends on the bow you are using them on. I tried the NV system on two Darton bows that were excellent shooters, but were a bit noisy, and had more recoil than I wanted. On the Maverick, they worked well to cut recoil. The bow still had some noise, but it was not too bad, especially when it was shot outside. The Maverick never did have a problem with vibration, it just had a solid thunk. On the Mountain 2000, the difference in recoil was also noticeable, and the vibration, which this bow did have, was also reduced. The Mountain was still noisier than I liked, even after putting limb savers, string leeches, NV system, and silicone caulk in and around the limb pockets. My impression from these two bow was that the NV system was much more effective at cutting recoil than noise. I still think that the regular limb savers (that you install on the limbs themselves) are the most effective Sims product. I have put them on over a dozen bows, and almost all of them seem to improve with Limb Savers.

That said, with the quality and effectiveness of all of the Sims products seems to be excellent. If the Extreme Limbsavers are cosidered an upgrade from the NV system, they probably work very well.