Will this work with a soda can stove? It has an open flame, so that is what I am worrying about. If so, would the 450 model be a better cup?
There shouldn't be any problem with doing that. I've stuck mine on a few different types of cooking fires/stoves with no problems yet.
A soda can stove with a wide burn pattern (like the Penny Stove) will shoot flames up the side of this narrow mug, which will make it less efficient than a wider pot. Also, the handles will get searingly hot.
On the upside, I do know that lots of people do use this as a pot for ultralight rigs. I have used it a fair amount for boiling water, and the writing on the side even holds up to moderate flame. You can even buy a custom lid for it from this guy's site. http://www.minibulldesign.com/apps/webstore/products/show/1232015
Hope that was a help