From what I understand, the advantages of propane are availibility, cost & safety. It will take a little longer to initiate the cut than acetylene, but in the case of the flame cutting machine I mentioned, the cuts were generally long, We seldom made a lot of little pieces.
That's what I was saying previously, we had used MAPP, tried Chem-o-lene, and now use propane.
The guys all grumbled when we switched to propane but there has been no noticeable change in production rates. Today, no one even thinks about what fuel the torches burn- it's not a big deal to us.
The main thing is that it takes slightly longer to start a cut - but not way longer. The speed of hand cutting is the same; cut quaity is the same.
How fast a cut can be made has more to do with the person holding the torch, rather than how fast the oxygen and fuel 'can do its thing'.
But in reality, the slight amount of time lost in starting a cut can be more than made up through being more effecient in material handling, welding, fit-up, and etc.
Keep in mind that we are a fab shop and that most parts are cut to size on a plasma table - so our hand cutting is mostly beam copes and that sort of thing. We burn way more propane in preheating, cambering, or heat-straightening than we do for cutting.