Thanks to all for the input. One complicating factor is that where I operate it has been known for the fire cover to be grossly deficient. Let's just say that the country has a lot of troubles which impact all areas of society, including the fire services, who do the best they can under the circumstances. That said, you just canīt expect a response equivalent to what you might get in a First World country.
Another thing is yes, getting people to sit around and wait for me to come to some decision, when even 50 seconds can seem like a very long time. Again, the society results in people being very mistrustful of authority, often with good reason.
An interesting double-bind is that I was told that my aircraft has a demonstrated evacuation time of 90 seconds. I would bet that was with a load of lightly-clad, highly disciplined and motivated, fit young men wearing running shoes. Not with the usual load of stroppy types who ignored the briefing, grannies, pregnant ladies in high-heeled shoes toting babies, etc. etc.
Then on the other hand I was told to expect some injuries in case of an evacuation, so that it's best to wait and evaluate the situation. Okay, but does that mean I can still count on getting my particular load of pax out the exits in 90 seconds? These two statements would seem to be self-contradictory.
Too, I was assured that the fire could be safely contained and extinguished by the aircraft structure and systems. This sounds like the briefing I got for my first parachute jump, the one where I was told the main was sure to open but if it didn't I had a reserve that was really, really sure to open....
On the whole I am indisposed to wait around trusting to the kindness of strangers, the cleverness of designers, etc. But I take the point about not letting a load of pax loose in the path of some fire engines, say. I'm still thinking this one over. Thanks again for the input.