In most cases i just used my chem and was fine. I can barely imagine situations where i want a ext atm ...
A whole lot of this. When I care, I always take double chem on a pyramidion (balloon and armor). It is much easier to chem and not worry about it than it is to hope that you don't mallet something just before it gets hit with stacks of fire (or even worse extinguish something only to have it pop up to 10 stacks again).
As a preventative tool, chem spray is more valuable to me than the reactionary abilities of the extinguisher 99% of the time.
Chem spray cooldown dropping back to whatever it was previously would be a good thing. With the fix for the flamer, chem does not need a nerf.
BUT
A radical idea for the extinguisher (that may or may not be possible):
Allow the extinguisher to put out all fires on a part
independently of the cooldown timer of the part.
Add the old cooldown of the extinguisher to that part when used.
Mallet a balloon and it gets set on fire immediately? Spray it anyway and put out the fire now, with the punishment of an extended cooldown before you can mallet again.
This would make the extinguisher an instantaneous reactionary tool, and allow it to be used the moment trouble pops up, as opposed to the current weakness that is the extinguisher.