Most of us would argue that canister gas is the safest. Can't spill it, and it doesn't go blazing up as when priming with Shellite.
Still, I've had a canister valve stick open after removing a stove, and I know I'm not the only one. Fortunately I had the presence of mind to screw the stove back on, but for a minute I stood transfixed with a gas canister spewing fuel. It's only by the grace of God that there were no fire or heat sources nearby. I hadn't given it a thought when detaching the stove. Gas stoves are safe you know.
There's a certain hut I read about recently that burned to the ground. Someone was changing gas canisters by candle light. Canister valve stuck open. No more hut.
Not trying to talk people out of gas. Just saying that there are dangers with every fuel. Except kero of course. The perfect fuel.
Seriously though, when changing canisters, don't do it near flame or heat.
HJ