Windmaster is bigger, slightly more effeciant with wind, has removable pot supports. The amicus has built in pot supports that fold down, less to lose. I have a windmaster, it works great, I can simmer with it. Taking the pot support on and off is a little annoying and it quite large, barley fits my 750ml pot with a canister in it.
I just did a test with several stoves and the Windmaster destroyed them all in boil time and fuel efficiency. It is bigger but I always have a cup for drinking coffee so I will keep the fuel in my cooking cup and the stove in the other. No big deal.