Here's what the EPA has to say about altenative refrigerants..
Best I can figure.. The reason why these alternative refrigerants are not used often are..
1 Not approved by auto manufacturer( someone paying someone else)
2 Illegal to release into the air, difficult to find someone to recover it. (probably the biggest reason)
3 That's all I have so far..
There's plenty of r-12 still available, and it really doesn't cost that much more.. A little more than double..
But, since I bought a Benz, I'm getting used to paying $60 for a $20 part