yeah, the simmerlite has a seperate bottle that you unscrew the cap and pour however much fuel in that you want. I believe (maybe wrongly) the iso-pro canisters are more like a disposable lighter, when it's empty it's useless.
I have been very happy with my simmerlite, but the windscreen is a must with this (it comes w/ one). I use it year round to cook for me, the kids, and the woman, or whatever combination is along.