I'm actually not experiencing any "klunk" at all in my car. It has never really been a consideration.
Sounds like one of those things if I happened to have it, sure, I'd install it.... but it isn't on the top of the list as "next purchases"
I'm actually doing quite a bit of research on a set of 6-point subframe braces, the Cusco from a-arm brace, and the reat trailing arrm T-braces. I figure anything that helps stiffen up the chassis and improve feel/steering response is a good thing