I basically agree with the R12 crowd now that R12 seems to be coming down in price. I converted my 300E to R134a two years ago when R12 was going up in price and people were predicting that you soon would not be able to get it at all.
I converted because of:
a. The dire predictions about R12 and its expense.
b. My compressor, manifold pipe and dryer needed to be replaced, so all I was out for the conversion was a new Schraeder valve and the two sensors.
c. The lower cost of the R134a offset the additional parts.
I did not change the condensor or the fan. I have been satisfied with the performance. It is comfortable when driving, but I would not recommend it to someone who leaves their car in the sun in heat and humidity on a regular basis. It just doesn't get as cold as R12.
And besides, I enjoy playing AC technician once a year with my can of R134a, my guage, and my collection of connectors.
BTW - the PO of my '73 280C converted that system to R134a, and it works very well, actually better than the 300E. :-)
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe