I agree that generally speaking any of those gasses are safe, considering how rarely accidents occur. Flashbacks risks are the same with acet or propane. Yes propane pools down but both systems should be used in a well ventilated area. Soot? I'm guessing w/ experience you set your flame quickly. And propane is noisier from what I hear.

I think propane is slightly more practical since it can be easily transported and refilled. This advantage is negated on a high production since it needs more oxy than acet. And using those OC is certainly interesting. I'll look into it as well.