Your post motivated me to finally get a gas heater. Found a couple that are similar to the one you opted for which I will purchase.
In terms of the gas to use,
this website says that propane can better handle colder temperatures hence why it's more suited for outdoor use while butane is better suited for indoor use with appliances such as portable gas heaters and cooking stoves. Also, butane can be stored indoors while propane should be stored outside. Living in a flat, I will have to opt for butane gas tanks. Hope to find them at a local home improvement store given the already high transportation costs.