To tell you the truth, I rank the boga-grip along with $500 abel trout reels and similar FF paraphenalia. It's not clear to me what that thing buys you (monster bluefish excepting), and also, where do you put it 'till you need it?
I find the inverted grip (thumb outside) works for big fish. Little ones I leave in the water until I can get a thumb inside. If the fish's really stubborn, I grasp it by the lower gill plate until I can get a finger inside.
Maybe someday I'll own one. I had a tough time with a couple of keeper-sized bass this sumer until someone posted the thumb-outside suggestion. Even with a bad left hand, it hasn't been an issue since.
I'd be curious to know your reasons for needing a boga-grip.