I got tired of the wondering every season if my A/C was going to need work in w126 and had my entire system gutted and professionally converted to 134. Every part of my system was replaced including the compressor and anything that touched freon such as hoses and other parts. I decided to do 134 because its more likely to be readily available in the future and with replacing everything I had the opportunity to do a proper conversion. My A/C is ice cold and comparable to the A/C in my w140 even though the w140's system is a superior design.

I think a lot of the misinformation about 134 is due to leaky systems that people just put a charge on without completely sealing and cleaning the system. The unfortunate truth is if you want really cold A/C your going to likely need the assistance of a professional that's able to correctly seal your system and get any moisture out of it with a vacuum pump. Pumping 134 into a leaky system with moisture in it would have a similar effect to doing that with R12.

People who willfully pump R12 into leaky systems because of cost are the reason why we had to change to 134 to begin with. Karma is a wonderful thing though. That moist sort of cold air must be great eh?