I can see how that would help, but I feel like a neckstrap eliminates the need for any of these fancy thumbrests by just taking the weight of the clarinet almost entirely off of the right hand. I have never used any of the ergnomic thumbrests for an extended period of time, but I did swap instruments for about 10 minutes with a friend who swore by his Kooiman. It helped some, but I still felt that pinch in the shoulder from the weight of the instrument. For me, that always leads to tension and tightness.
The biggest problem with clarinet neckstraps for me has always been that they interfered with the left thumb enough that I just couldn't get used to them, so I picked up Stephen Fox's thumbrest mount neckstrap rod, which is the second item on
this page. It replaces the stock thumb rest and has a threaded mount for an included rod that has a strap loop on the end of it. It holds the strap out from the body of the instrument a bit so that my left thumb can do what it does without hitting the strap. I took it to a tech to have it installed, but the holes lined up perfectly on my modern R13 (2005) to replace the adjustable thumbrest, so I could have probably done it myself. The rod threads on and off in a couple of seconds and when it's off, the thumbrest feels totally normal and, crucially, it fits in my case without any modification.
I'm pretty pleased with it. I have had intermittent issues with the nerves in my arm and shoulders related to holding the clarinet since I was getting my bachelor's degree over a decade ago. Now that I work all day on a computer and then play clarinet almost every evening, it has taken a lot of management to keep carpal tunnel-like symptoms at bay. When I use a neckstrap, those are almost entirely gone and now I can finally have that without the annoying left hand thumb interference. I can play faster and more evenly almost immediately once that unnecessary tension is gone.
And at $25 for the replacement thumb rest and rod and $20-$40 for a strap, that's still a much cheaper experiment than that thumb rest.