As I said. "Obviously they have to contain 'all the works' (oscillator,
balanced modulator, compressor, clipper, filters, balanced demodulator
etc)."

That sounds very complex and expensive all right.
Another problem I see is that they only work on SSB.
My customers insist on something small that fits inside the radio and
processes in all modes. The VoiceMax does that with less than 1% THD.
Can't build them fast enough to keep them in stock...