The Ultimate Zapper is still available. It is, by far, the most powerful, most effective zapper in the world today.
I doubt it. I have an Ultimate Zapper. I opened it up to see what was inside. Looked like a basic Hulda Clark design on a little bread board. I would guess the timer chip had its duty cycle changed which is adjustable. A clever trick was also used to raise the voltage. I didn't go into detail and look up all the components to find out exactly how it worked but I am a trained professional in electronics. Maybe the circuit is altered a little to stabilize the signal under load but it is no big deal.
I believe Atelier Robin may make the most powerful, advanced, versatile and effective zappers in the World.