First, the reason I tried it was because I have long suspected that Enviro-Safe IS propane.
And I don't use alternatives for money. It is for performance and versatility. Enviro-Safe, and possibly propane, works in both R12 and R134 systems, so I don't need to mess with "conversions" and it works better.
We don;t seem to worry about gas leaks. We treat them as a simple nuisance. But when gas leaks it comes out as a liquid and stays liquid for some time. I will not put a rubber fuel line over an engine. But I have had rubber AC lines blow off over an engine. If the whole three pounds of propane leaked out it would flash off and be gone.