john_smith - I respectfully disagree.
A highly-respected TRE taught me during my command course that the decision to evacuate can be changed right up to the point you actually give the command, i.e. at the end of checklist. If the fire is put out after commencement of the checklist and subsequently it becomes clear that actually the aircraft is safe and will remain safe, it is not mandatory to evacuate just because the checklist has been commenced.
Of course in the sim we invariably practise it to an evacuation and how it would work in real life with panicking passengers and cabin crew primed for an evacuation is another story entirely.