ENOUGH ALREADY!
You are going on and on over nothing here, as you point out you can have large differences between compound bows using the same technology.
Ask any of the serious hand loaders here, like Dick 284, no two guns will shoot the SAME load equally. I load for a lot of guns and people and I have seen as much as 180 FPS difference between identical makes, models and cal shooting the same batch of hand loads.
I'm not sure why the efficiency between bows became important to you in this argument perhaps you could remind me?