I do have to have fire extinguishers in the catwalks and they are on proper mounting brackets. We even have a company who checks the pressure and condition of them about once per month. Vegas does have fairly high standards when it comes to fire codes. Monte Carlo excluded

I'm just torn between the policy of no lose items in the catwalk and the possibility of causing a hindrance in an emergency situation. The fire marshal said that it was a good question and that he would get back to me. The insurance company said the same thing. I think that this whole thing comes down to my OCD about lose items overhead. Being a former rigger I've seen a couple of close calls.
Another anecdote about the CO2 extinguishers. I was on the road at a fairly shabby theatre which I won't name. Everything was up and running during sound check and I noticed a stagehand on stage left using a CO2 extinguisher on an electrical panel. After inquiring why he was spraying down the panel he told me that this was how they cooled it off during shows so that it wouldn't melt or trip a breaker or something. I would have been concerned but he was so casual about the whole thing that it seemed like just part of his daily duties. The show went off great but there were a couple of times where you could hear a short burst of the fire extinguisher.
Oh and some interesting news in the world of cirque.
http://thestrippodcast.blogspot.com/2008/01/breaking-mysteres-days-are-numbered.html