DOES THE HDK SUSPENSION K-MEMBER HANDLE BETTER THAN A T-BAR SUSPENSION?

Not really....I re-read your guess and reasoning and it sounds to me like someone attempting to do a book report on a book they never read.

The only thing that makes sense to me is you apparently have no idea the function of the HDK rear brace and makes me question whether or not you have any real world experience of actually building (yet alone installing)......anything.
I'm game, now please be specific in what is not clear that you read or I shared.
Your major in college was? I was given an "A" in technical writing my sophomore year, but I might have lost a bit off my speedball in the decades since.
So where were we, you are going to point out where I lose you in my "book report" so we can have some mutual understanding on the downsides of using swivel connections on bracing on a car chassis.