I think it's great that you took a stab at a unique design and demonstrated that it works. I have mocked up a couple different tab shapes and always wanted to trial them out but never have. In that process I spent quite a bit of time studying the different tab styles and I'd be curious if the difference in performance is simply related to the total and projected surface area presented to the water at the ideal deploy angle. e.g. the silver tabs at 5 degrees present less projected area and total surface area to the fluid passing over it versus the black tabs and also have less surface area directing water outward thus generating slightly less yaw.
Deploying them further would increase the projected area similar to some other mfg's but it would also increase total lift on that side decreasing overall wave effect. Your addition of the inside down turned flange as well as the outward angled fins adds to the amount of projected area as well as redirects water outward instead of only downward generating more yaw at less overall lift. I'd be curious if slightly more fin height or angle and/or more inside flange height or angle could bring the performance closer, but in a smaller (and more manufacturable) package. I've also wondered if it would be possible to have a base tab surface that deploys to a set location for the ideal amount of lift and a second set of surfaces that could be controlled/adjusted separately to vary the amount of yaw generated.
I've noticed that newer MC's use tabs that no longer attempt to direct water exclusively outward/downward, but instead include down-turned flanges on all sides. However, the tabs are mounted at an angle greater than the deadrise of the hull such that when deployed they naturally generate slightly more yaw and slightly less lift while still generating substantial overall drag to yaw the boat.
On a totally different note, I noticed you used AL instead of SS and you also mounted the hinges above the tab surface rather than below. Any reasoning for this approach?