I have limb savers on one bow and shock fins on another. I agree with your findings.
I didn't test them as technically as you did I just played it by ear and the Shock fins made the most difference. Not only that but they were on clearance when I got them, I just bought them to give 'em a try since they were selling on clearance for $5 I gave them a try and I am impressed. I am thinking about buying the remainder at the store and tossing the limb savers. Maybe I'll use the Limb savers for the end of my stab.