We had CNG for 20 years, now have propane, and would never go back.
In addition to the difficulty of finding refills (impossible outside the US, which may not matter to you), you have the problem that you have to refill them very often: each tank stores very little energy (by comparison to propane). Full-time liveaboard/cruising, we get almost 3 months out of a 20# tank of propane. In large measure, these are the same downsides to alcohol-fired cooking: you often can't get it, and it produces little heat for the volume it takes to store it.
If you're that scared of propane, would it make sense to you to get a diesel-fired oven
/stove? The fuel
is safe and available, and you're probably carrying some already. There are other tradeoffs, of course, which is why most people eventually wind up with propane.