Everyone's entitled to have their opinion, so let me give you mine. I have used EnviroSafe Industrial 12a (refined propane) as an a/c refrigerant for over 2 years now, and it measures colder than R12 did (at the vent). Also, propane is, and has been, widely (and safely) used in Europe as a refrigerant in tractors, cars, trucks, etc.
A lot of people will say it's dangerous. But it's not, and here's why. All fire requires three things, air (oxygen), fuel, and fire. Two of three are not present in the a/c system. Should you have a leak in a propane charged system (regardless of small or large leak), the propane will simply dilute in the atmosphere and float away. Most a/c leaks are minimal and take weeks or months to take place. That small amount of propane will not burn. By comparison, you should be more concerned about a gasoline leak at the base of your carb or fuel injection dropping fuel onto a hot engine/exhaust manifold. I suggest you read the arguments for propane before assuming it's the devil. -Just my two cents.