Halon does make it a challenge to breath, but then again, it's a fairly open cockpit and if you mount a discharge nozzle under the dash, it's distributed at your feet more than your face. Besides, fire eats the oxygen as well, so either will make breathing hard.
I don't know if Halon is heavier or light than air, and that might play a factor in breathing. Of course if you flip the car then discharge the system, and the stuff is heavier, you now have a face full of it. I do know that there are alternatives to halon, but they all have some kind of danger listed.
My system has three nozzles. One under the dash, one on the firewall (top, middle), and one in the rear. Top of the rear, middle of the rear firewall. Bottle between the battery and fuel cell. What I don't know is what it contains, so I guess I'll have to remove it and see. Besides, the gauge is mounted facing down. No way to see the charge state unless I crawl under the car, and I'm a pretty chubby feller, so would have to jack that car up a few feet to get under it. Also the label is nowhere I can get to.
Seems like a good setup all in all though. I know that some would rather use a hand held extinguisher than a fire system for weight as well as control, but I think I'll take the weight hit. What the heck, it's already installed and functional. I've got enough work to do this winter.
Mike.