I'll take a double scoop of both.
I already knew one set of radials needs to be 90* out of phase to achieve CP.
I just figured if the seller was marketing his harness it would be most likely to
folks who neither knew nor cared. Furthermore, if you are selling something
why tell them how to make it?
Robb gave us the link to Maco's new item and it describes the item to a "T", but I didn't check it out at first, and that is what I asked Robb to describe. Then the discussion, and seemingly nobody checked out the link.
That harness may do what they claim if the installer has all of his ducks in a row. Like the video guy said clearly, both radiators need to be pretty close in all respects too, and that can be an issue if not watched carefully. That is also what QRN said in his remarks.
I can't say how much difference it would make, but it could be important to check. That is why we use to recommended on the co-phase harness packaging the proper way to install them on the rear bumper of P/U trucks only, back in the day. This could be like co-phase harnesses too, most will probably show a good enough match, and that is what most CB'rs look for when they install something new. But, when they get through...all of a sudden the thing is better that sliced bread regardless of how it really might be working. This dosen't happen in every case, but it happens.
IMO, there is a little more to doing new things, rather than just stumbling around in the dark...without any effort to try and understand. Homer, I think you're far more aware, cautious, and understanding than most, and your goal is likely always trying to really see just how things work and perform.
Not so much with most others, I guess that was my point.