Do fork braces make a significant improvement for our bikes? I am concerned mostly about interstate highway stability.

I had the TKAT on one bike and I have a SuperBrace on my current bike.  I drank the snake oil.  Whether is purely psychological or if it’s actually real, it seems to offer modest improvements.  I notice it most when using the front brake on rougher roads.  That said, I don’t think these bikes can really ride true above 65mph no matter what you do (the Cafe mod people will disagree with this comment, but they’ve put a lot of time and money into those mods).  The bike likes to “float” with its stretched rake and light weight (chopper style).