an unextinguished engine fire inflight, worries me a LOT less than an inflight fire in the cabin or belly.
Odds are, pulling the engine fire handle will extinguish 98% of all enngine fires, unless the fire is a magnesium fire. (then you might be hosed).
Even the less modern freighters have belly extinguishing, but the main deck is the achilles heal.
I just got out of the sim and we did the fire drill with masks and goggles on, and tried to run the various checklists as best we could. That shed a lot of light on how difficult it is to communicate with ATC and your colleague in the other seat, and fly the plane and configure for an approach and program the FMC and work the MCP. I encourage all the cargo rats to try this drill in their next PT just for your own enlightenment. Human Beings are not very good at multi-tasking!
Carrying HAZMAT is not all that dangerous as long as you know about it. Its that undeclared stuff that worries me.