I replaced my condenser with a parallel flow over four years ago. The capacity is indeed smaller but I think it's been working great so far. I originally installed Freeze 12 and work fine with it. But then I put in R12 shortly there after and it has been great. My only regret is pulling the evaporator out to give it a good cleaning. I feel the air flow from the vents is restricted somewhat and a good cleaning of 27 years of crap should open it up a lot.
Here some pics as installed 4 years ago.
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