Hi richnz; you're right about R134A being a joke in systems not specifically designed for it. It also tends to ruin compressors which end up running at an insane high pressure. I fought that battle since the R12 debacle became a thing.
Before using R152A in my cars, I did some flammability studies on it. It seems to be very difficult to ignite. In fact, it will extinguish a propane torch quite instantly. I believe that when combined with certain other materials, it could have more flammability than it does when spraying out of a duster can. I had to solder a puncture in an evaporator of an old fridge, after an attempted R152A charge. There was a tiny, candle-like flame that existed only while the soldering torch was present.
I sprayed a lot of it in liquid form onto a paper towel, and that was able to ignite. It seemed to burn only because the paper was already sustaining it.
When sprayed in gas form, it would not ignite.
Bottom line is, for a car A/C you would already need a catastrophic fire in progress before the refrigerant would become ignited. There aren't any substantiated accounts of R152A burning accidentally in a vehicle due to a leak. It's just not a valid worry. If you already have a catastrophic fire in progress, there are other things which are present in higher quantities, and burn with a lot more heat.
The main reason I like it is because it's not a blend. There is only one compound in it. If it leaks, you have less of it but you still have the same thing. It's not like a hydrocarbon blend that separates if it leaks. You can recover R152A and re-use it. There are so many benefits to it compared to the other things you can use.
