As a followup, I bought a Synth9, and yes it works fine with your voice. I’m feeding it from a channel insert off my mixer, but it’ll probably work OK with a dynamic mic straight in. It is very sensitive to background and handling noise, so I think putting a gate ahead of it would be helpful.
I also used it with my EXH V256 vocoder. It’s excellent this way. The Synth9 presets go well with a vocoder, and it eliminates the need to play keyboards. Just sing, that’s it. You will need an xlr male to female 1/4″ adapter for the mic in on the V256. I feed the Synth9 off an insert on a mic channel, send the dry output to the mic in and the wet output to the instrument in on the V256. I also used an female xlr to female 1/4″ to be able to use the effect out on the V256. If you want to sing with your natural voice, just hit the mic bypass switch on the V256.