It does sound like you have fulfilled the legal requirements for using hydrocarbons, unless it is locally prohibited. However, PLEASE label the system VERY well to indicate the contents. You could save a future serviceman a lot of headache and money.

What oil should you use with ES? If I recall correctly, it works with POE or PAG but prefers good old mineral oil. Thus the two-step conversion process is really bad for running hydrocarbons.

I would flush the system and replace the oil with mineral oil to use hydrocarbons. You will be a lot happier in the end. (Of course, I would stick with R12 or R134a though.)