There's no right or wrong, however your stubborn and closeminded attitude doesn't do you any favors. You've chosen to disregard a proven and superior technique because you have decided, without even trying it, that it won't work for you.
A constant in many threads besides the highly opinionated answers is that often a person will start a thread and ask the wrong question expecting to get right answers that support their often incorrect way of thinking and get defensive when few or none agree with their suggested technique.
Fair enough. I'm not sure if you consider my thread a "wrong question" reflecting an "incorrect way of thinking" as well, but in any case, I think you've made your point.
Thank you again for sharing your feedback, views, and experience — especially about your transition from a backmounted to a slung pony — which I'll keep in mind.
This might be me being stubborn and closed-minded again, but I'll personally stick to discussions focused on the thread topic, which is advice on actual backmounting systems people use.
There have been quite a lot of useful and practical contributions, covering 4 distinct backmounting systems so far.
Meaning I'll deliberately avoid taking part in slinging vs. backmount vs. sidemount vs. twinsets debates altogether from now on, as I think pretty much all has been said.
Our differences don't have to divide us.
Cheers.