RE: "Flammable" Refrigerants
If you read through the various spec sheets/regulations etc.  you will find
that in fact the alternatives to R134 are legal and do get used in heavy
equipment, farm equipment, etc.  Off road stuff.  That's how they are
staying in business, that's the market those products are aimed at.  They
are "Not Approved" for passenger vehicles but not banned (except for some
states like my own Soviet of Washington). And IIRC there is a provision
that allows them in passenger vehicles IF they have previously been
converted to R134.  And I also recall reading through the government spec
sheet on a whole bunch of refrigerants and under flammability the entry
said "Not Tested" for those containing butane so we don't really know if
there is a hazard or not!  Maybe someone that is about to use some of this
stuff in their Vanagon could do a test (see YouTube under 'hair spray and
lighter') and tell us what the result is:)