I live in west central FL. and YES duracool works and works fine. Street temps EXCEED 140 in the summer and I stay cool. Trick to duracool is you MUST ignore charging pressure and use VENT temps when you charge the system. R12 is the BEST way to go but if like me some ********* had convinced the previous owner to switch to 134 it is the ONLY option to consider since it will work with ANY oil. The work and cost of switching back to r12 stopped me from going that route. You have an r12 system now so if possible stay with it. If not possible look at duracool as it works and works quite well. You WILL NOT blow yourself up. This is total BS and if it happened as much as "some people" on this list tell you it would the sellers of the stuff would be locked up by now and charged with murder. We are talking about 12 ounces of flammable gas in a car that has 7 qts of flammable motor oil, 20+ gallons of diesel fuel, and several ounces of brake fluid under the hood that could also burst into flames in an accident.
My 300d had 134a in it when I bought it. My kids 240d had been converted as well but the old style York compressor sounded like it would fly apart when it ran. I read all the info out there on different stuff and tried the duracool last year. When I looked at vent temps way colder than what the 300d put out as well as pressures about 1/2 of 134 in her car I decided to convert my 300d as well. Vent temps went down 20 degrees in my car and the pressures went down 1/2 as well. You can't feel the compressor "hit" in the 300d anymore when before it felt like an anchor had been dropped when the A/C came on.
Screw the it's illegal in many states to use a flammable gas to charge any system. It has been many many years since I took the governments word at face value when it come to what is in my best interest.