I bought a VoiceMax to see what it was all about, set it up per the instructions, and it did what it said on the tin, loud, clear audio.
The noise gate was useful in the mobile, being very effective at reducing road noise. This little device is extremely well built and works well within its design limits, being great for long winded local qso, the audio being very easy to listen to hour after hour. That said, it it is no match for any of the quality RF clippers mentioned, in a DX environment, nor was it ever intended to be.
It would be interesting if Telstar Electronics would produce a dedicated RF clipper and satisfy this end of the market, apart from Ten Tec, to the best of my knowledge, there's nothing else out there that works correctly.