I can confirm the WS1000 is supported in RealFlight 9.
Basically, RF9 has the exact same level of controller support as RF8, plus enhanced support for the InterLink DX and some other controller mapping improvements.
For example, you can now combine two buttons to behave as a tri-state control. This is used a lot in the new InterLink DX radio profile, but it can also be helpful if you're using a controller with fewer than 4 axes. On a gamepad, for example, you could map the left and right shoulder buttons to the rudder. It would be centered most of the time, and pressing a button would give you full deflection in that direction. It's not ideal, clearly, but would be preferable to having no rudder at all, or having it stuck at full deflection.