Another thing I'd like to throw into the debate:
I think the 8-fire-stack-gun-kick mechanic to be very unintutive. Personally I didn't realize what's going on until I read up on it on the forum. Perhaps due to the lack of ingame feedback for the event (you just get kicked out - no further animation/message to emphasize something special is happening) I stood more or less baffled next to the gun and spammed E the first times I got kicked off by flames.
I will continue to repeat it many, many, many times:
Better (mandatory) tutorials.About the rest - I've had some ideas
1. Make flamer more disably and less killing - in a meaning that it will decrease the guns damage and turning speed by up to 50% but the gun will never be too hot to use (but it will get regular damage from stacks like now). Still good enough to use but less annoying for defender.
2. Make a default "second use" for wrench / spanner (or make a slightly worse version with that mechanic) which will allow to decrease fire a bit, say 1 stack per 3-5 second cooldown. It's not much enough to drastically change the game but it's something.
3. Leave everything as it is except decrease flamer range by around 30%.
4. Make a new version of chemspray with longer cooldown but also longer protection (so the secondary engie can chem things from time to time).
As sparklefish said - the flamerthrower is a very deadly weapon which requires very little skill to use. For me it's ideal noob-bashing tool because most players below 5-ish lvl don't ever use chem, so one accurate flamer clip can disable the whole ship.