Oxy propane does not use more O2, if the regulators are set correctly.
Yes, oxy propane is colder than oxy acetylene, but it has more than enough heat to cut steel. Propanes higher BTU value (the ability to transfer heat) helps as well.
Using oxy propane over oxy acetylene can give a reduction in cost of 30% or more.
Yes, the cut needs a few more seconds to start, but how many of us make enough cuts during the day to make a real difference. Cuts with oxy propane may take as long a 4-6 seconds longer to start, but you will find a somewhat smaller kerf and less gas used. If you figure 100 cuts a day with an average 5 second increase in starting time, you are still looking at an 8 minute difference.
The slag from oxy propane is also much easier to remove.
You will find the same benefits from oxy natural gas as well.
Also-oxy propane does not "burn back" as easily (won't say it can't be done, but it is tough if you are treating your equipment properly and is not as hard on your torch equipment as oxy acetylene.
Give it a try-an honest try.
If there was a cheaper way to cut, you woudn't see all the scrappers on oxy propane.
If you still havetrouble, let me know directly with particulars.
Good Luck
brande