From my experience, which is very very shallow, any ship other than the Mobula and the Spire handles fire fairly well. However, every ship will have one or more components that is very hard to reach.
Goldfish's main engine is almost never reached mid-fight.
Pyramidion's top-deck components will almost never be worked by the main engi.
Junker has the top two engines that is hard to repair.
Squid's back gun is almost never tended.
Mobula's hull and balloons are hidden below deck.
so on and so forth...
It is a good idea to spray these components before a fire fight.
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When it comes to a comparison between extinguisher and chem spray, there's no clear winner, as their usefulness is situational.
Chem Spray will hard counter flamethrowers and other flame-based disables. With clever application, the spray will enable your ship for the duration of a skirmish. But if a component catches fire, the sprayer has no choice but to let the component burn out.
Extinguisher lacks the power of the chem spray, but with the extinguisher, the engineer can better focus on repairs and rebuilds.
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I think the general rule is to have one chem spray engi and one extinguisher engi.
By the way, never run extinguisher and spray at the same time. That is the mistake for a nincompoop.
Thank you for reading,