Not to play Mr Science which would not be a convincing role for me, but I think the ratio of Oxygen consumption is pretty much fixed by the underlying chemistry. There may be some torches that are a little more efficient than others, but I don't think you can move the markers that much.

"oxy/acetylene burns at a rate of 1.1 parts acetylene to 1 part oxygen by atomic volume, and oxy/propane burns at like 3.8 parts propane to 1 part oxygen." Not really sure what that means when one gets down to the actual weights of gas in the bottle, etc...