On a related note, it's not always whether Dickies or whatnot may offer protection almost-as-good, but we find a good deal of people want permanently treated fire resistant gear, especially something that is ARC rated. With more fire departments becoming more conservative, some are thrilled to see that performers are using rated clothing. Case in point, our local fire department is impressed to see ARC rated casual gear (such as t-shirts and turtlenecks).

Will such clothing help you any more than Dickies if you get soaked in fuel and set alight? Probably not. But it is nice for big fire, safeties, and those times when you get tangled in a normally-unprotected spot. The bonus of being able to tell the FD that you are using ARC rated clothing (and other fire groups aren't) may make a difference to your reputation. Is an amateur going to benefit as much? Maybe not, in which case the spot protection Sam brings up makes sense.

Examples of shirts and other rated gear:
www.flammaaeterna.com/c-25-apparel.aspx

Matthew
Flamma Aeterna

I wavered a tiny bit on responding to this, but ultimately thought I would. After a lot of our own research we ended up carrying a good line of fire-resistant clothing (specifically types of clothing that fire-dancers and safeties wear). Personal experience with what I have used has brought me to the belief that rated gear generally outperforms anything we normally wear. Granted, if something soaks up fuel and gets set on fire, then it won't matter either way, but the permanent fire resistance treatments I have found to be worth it, especially for big fire and safeties.