I've got both a happs 3 inch trackball and a happs 3 inch Highlip trackball.
If I had to pick which one I like better, it would be the highlip one. I've got that one on a GT cab that I built. (it's actually a GT fore control panel that has no mounting bolts on top at all so its all flush.)
My regular 3 inch trackball (now gathering dust) was mounted with the top mounting plate. So that might have been why I like the highlip better (no bolts, etc.)
I'm reusing the same happs ps2 interface on the highlip that I had on the regular 3inch ball.
They feel the same as far as responsiveness goes, I guess I like the BIG BALL, baby. Especially on GT, World Class Bowling, Shuuz - it feels like you get a better piece of it when you wail it.
My 2 cents.
Smack