So I want to come at this from a little different angle and give my input if for nothing else to maybe add a different perspective.
I have an old moto racing injury(one of MANY)that left me with a severed ligament in my support hand thumb, apparently the one that gives you dexterity and vertical movement. I can still make a fist and apply downward/sideways pressure, but that's it. I cannot extend my thumb like the rest of my digits when I'm establishing my grip on the gun nor can I control the amount of sideways pressure put into the frame of the gun when gripping hard(as we do)and is something I have regularly struggled with from the beginning learning to shoot a pistol.
I shoot a Tanfo Stock 2 and my thumb regularly jams into or hangs up on the slide stop lever, rides the slide and I have also had my thumb end up inside the trigger guard when training fast draws and reloads in dryfire.
Recently at a match I was handling a friends limited gun that happened to have the Nitro fin on it and I can honestly say that was the most comfortable and firm grip I have been able to apply onto a pistol - EVER. It felt amazing - I actually felt like I could repeatedly put my support hand in the same place with even amounts of grip pressure.
So personally for me it has zero to do with the effects or benefits it has on recoil control and has absolutely everything to do with finally having a place to put my thumb where it wont interfere with grip pressure, how the gun tracks, or re-establishing my grip after a reload or running, etc.
That being said, I am willing to do whatever necessary to comply within the rules with how this applies to production(i.e fitting the box, etc.)and have purchased one in the interim to test and experiment with. Cheers guys.