All of these are big knots using lots of rope length. I don't think one version, so much more so than another for situations where you'd be looking for one of these.
Tie this, tail-collared bowline-on-a-double-line and the return leg u-turn version both before talking about the ring loading difference. Again, I think, depending on how you configure the ropes inside the nip, you might be surprised how similar they actually are. And I think when you ring load it, that configuration I mean will emerge anyway.
What happens is inside the nip, the lower "collar" parts/splits around the outgoing eye legs. This is especially true for the cowboy version where it basically doesn't go go around those at all, but just emerges to either side of them from within the nip. It is not collared. That's why it's hard to tell the difference in the versions. The only difference is if the lower collar legs emerge on the same side of the outgoing eye legs, or on opposite sides. Either way, they don't go around them.
Furthermore, there is no need to snug this end-loop up tight. This is two bowlines, those are its tails. The only reason it even needs to be looped around something is to give it slack security.
So as has always been true I think, use the cowboy version for ring loading. That doesn't bother Tex at all.
I agree with your basic points about the purpose of the collar and I also agree with you, over D.L's objection, that, in a normal bowline, the nip cannot work if there is no friction on the tail going through it. I haven't convinced myself that some of these knots you show keep the nip doing its job well instead of cheating by overloading the collar, or the secondary collar formed by the end loop. Yes if that end loop torques the nip the correct way, it might work even better than a bowline (but not exactly the same as the bowline), getting a higher ratio of nipping force to collar tension, so I should play with it.
(and yes I meant two main loops)