Nice.
All that nonsense about propane is a load of bull. Consider there's only like one or two pounds of propane in the system. Even in the absolute WORST case scenario (that is, assuming a line bursts and something inside the unit is already on fire) there will be a bang and all the propane will have burnt up in an instant. Not a big deal. A more realistic scenario is that it develops a leak and that catches fire... in which case you'll have a little flame for a minute until the system is empty. But really, any leak is never going to have something sparking or at ignition temperature right in front of the leak. Besides... that new garbage refrigerant R1234y is flammable too, and somehow, that's A-ok. Let's not talk about the deadly toxic fumes it makes when burning, either.
Also, literally all of the 'incompatible refrigerant' argument is sort of a moot point. Because it's not the gasses that are dangerous to mix, it's the oils with the gasses dissolved in them (think CO2 dissolved in soda). Not even the oils themselves (although there is some technicality to that). Once the system is under vacuum, most of the refrigerant bubbles out of the oil, and that's that.
/rant
