Funny how I have been looking into this myself, here is a good thread:http://www.fiero.nl/forum/A...130314-2-119626.html
People have stated that the R12 does tend to get colder. If your AC system doesn't have any leaks, you could recharge it with R12 at a mechanic shop. R12 seems to have gone down in price recently due to it being out dated. I will probably go that route, and stick with the original stuff myself.
Just my .02