Politics, price of refrigerant, etc., have nothing to do with the downside involved with junk refrigerants. All of the junk refrigerants fall into one of two categories, they are either a blend or flammable.

The downside of a blend is that the components leak at different rates. This presents problems on two fronts; one is that to achieve the blend balance after any loss of refrigerant requires complete removal of the refrigerant, disposal of same and then recharging from scratch. Also one of the components of a blend is included for the specific purpose to circulate lubricant. With the balance upset, assuming the correct lubricant was used in the first place, lubricant will not be properly circulated.

The downside to a flammable should be obvious. As of about five years ago, flammables were completely outlawed in 18 states and the District of Columbia, this list of states might be even longer today.

I have never heard a reasonable justification for using any refrigerant besides 134 or 12. Both of these refrigerants are plentiful and inexpensive. In todays market 12 can be had for about $20 per pound and 134 for about $6 or $8. Any money saved by using a junk refrigerant will be eaten up in the conversion, lack of long term reliability, risk, problems finding someone to legally deal with it and on and on and on.....