That's a great idea! It keeps the main panel clean, and allows the trackball to be used when needed. In fact, you could use the ball to navigate the os without "deploying" it.
I have used those brass supports, and they're OK, but I think I might make an additional wooden support for the middle and use a piano hinge along the joint.
As long as it's working for you no reason to change it though!
I think I'll steal it for mine! I'll probably add a spinner to it too, and maybe a dedicated 4 way off to the side. I'll need to think long and hard about that, and be really, really careful about how high it is!!!
Bob