I failed to mention that I don't wrap the foil tight around the circumference of the pot. but allow heat to dissipate upward, rather than be forced back down to the canister. My prime goal is to block drafts. It quickens boil times, but does not reflect a large percentage of the heat back down to the canister and create a dangerous situation. If you research the chatter about stove explosions (I did when I started to use a canister instead of a fuel bottle) the greatest incidence of explosion and failure is brought on by large diameter pots, i.e., a frying pan. Your tests are good and have given you confidence in what you've chosen to do. Common sense goes a really long way. I've never had the canister hot enough to burn a finger, let alone blow up. OM's advice is good- I can't imagine taking any chances in dry conditions!
I can't recall ever walking away from a stove, but I imagine there are those who do....