Julian265, the setup I'm using doesn't use off the shelf joystick parts. It's all scratch built. I'm using a BI Plasma MM2 as the interface and the input curves can easily be adjusted. Keep in mind that standard pots have a 270 degree travel and most of that is wasted in joysticks that are using them.
The primary benefit here is a noise-less (electrically) system that doesn't cost an arm and a leg. A good quality pot can run well over $10 each.
I don't understand the linear vs sinusoidal thing though. If you've got a stop at 0 and a stop at 180, you're going to get a linear response line. Yes, if you go beyond the 0 and 180 points, it's going to go odd on you, but that should never happen with the kind of mechanical systems we're talking about. I suspect you may know something I don't however, so educate me!