" I can even see another way to get signals in which is to use an RC transmitter and use the sticks."
You could - but have you ever tried playing a synthesiser with a joystick or bend wheel? - I have! ;-)
Even when driving a simple analogue (Mono) synthesiser from any controller like J/S or whatever, I find it near impossible to play tunes accurately - the nearest I ever got was when I tried to replicate a tea-chest bass using a single axis heavily loaded industrial joystick (this joystick came from a demolition vehicle ;-) and a twangable trigger device (a sprung door stop with a piezo wire wrapped round the spring).. It did seem that it was easier to play when it was heavy force needed (emulating the action of stretching a heavy string) - the tea chest bass is a tea-chest (or other suitable square box resonator) with a string connected to the centre - one has a broom stick which pivots on this box, the string connects to the top of this stick, and one stretches the string by pivoting the stick - and plucks the string.. It shares the same problem as the theremin in that one does not know the pitch until it is plucked..
But I still found the tea-chest bass easier to play - I personally wonder whether ones hands actually 'feel' the resonance even before one plucks the string - a feedback completely missing with an electronic version - so I was planning to vibrate the joystick a bit to test this idea --- but some other distraction came along...
Fred.