Your pot support sounds like it's very constraining to the airflow, which might make it not work as advertised.

I get approximately what is claimed on the site with penny stoves made about like he says. I use a small pot stand made of coat hanger wire, two "U"'s with one set of uprights wired together. I then use aluminum flashing or an msr windscreen around the pot, but the pot support might be what is causing you grief.

Here's my setup in action:


You can see how my windscreen is not the pot support. That morning is below freezing (you can see the frost) and it boiled up 3 cups of water on about 3/4 of an oz of alcohol or so. If you look carefully you can see that's a canadian penny




I think my pot is about 2cm (slightly less than an inch) above the stove: