Thierry,
I know that you and some other people here at TW have been waiting patiently for evaluation samples I promised - but have probably given up by now!
I am getting real close to having kit to ship - Most of the modules are now prototyped and working, some minor issues require sorting - but early next year you will be getting a Theremin Developers Kit from me.. This kit will allow you to construct a Theremin to taste.. It WILL be worth the wait! The only thing the Tvox can do which my kit will find difficult, is giving the non-linearity the Tvox has..
My sensor modules give a voltage output (0 to 10V linear to distance from antenna to 1M at present) and VC electronics is used for sound generation, so 7 octaves is no problem (playing range is a function of how much one attenuates the voltage, and tuning a function of how much voltage one adds or subtracts).
If you can wait a little longer, you may not need a Tvox!
"I will loose or even waste too much time and/or money"
I know the truth in the above statement! I made some big mistakes, and shifted my focus too often, which made life more difficult - but even without those errors, the task of designing a good Theremin has been far more difficult and expensive than I imagined.. If I had seen the future a year ago, I would never have embarked on the project, and would have bought an EW-Pro and been about £20k wealthier today! (I could have taken on more paying work, instead of developing these damn Theremin products).