Cool - I am tempted to try it, even before I convert back to R12!

I'm no expert but common sense makes me wonder...

If R134A is less efficient, cools less, takes longer to get cool and runs with higher pressures (works harder), does it not in fact require more energy (fuel) to operate?

bingo[but dupont doesn't care about that.their patent had run out on r12 so they got the gov's and scientists together to push their agenda and sell a new refrig.does it work as well? who cares does it make more money for dupont than letting everybodyelse make r12 without paying royalties? YOU BET]

Couple of other cost effective tricks for checking high thermal load in temperate climates..
You can lower the cut-in of the termistor range of the collant temp sensor by bridging it with a parellel resistor..this gets you a 100C cut-in of high fans [ instead of 105/107 spec.] when the a/c condensers passive heat starts to effect coolant temps [ which it always does with the cond in front of radiator]..this is a $2 modification that we have been using for years.
The other is many use a cabin sw that shorts the high pressure sw manually..this is nice if you want to get a jump on temp creep-ups at will.
Good as a high temp saftey measure , regardless of using the a/c or not..great if towing, etc..
This also allows for normal operation when not being used b/c it does not change any of the circuits stock design. { Had to throw that in there before I get jumped on that one..:)]
Also, you can jumper the R15 dropping resistor to get high fan instead of low for a/c operation ..this does require running a heavier wire back to the low fan relay as the original will not carry the higher amp load of high fan [ you will notice high fan and low fan have different size wires , as low fan does not have the high amp draw of high fan, due to more resistance in that circuit from R15.}
And lastly, don't make your coolant ratio on the high % range...water transfers the heat away lots faster than anti-freeze does ..40/60-h2o is fine in temperate climates..
These are just simple , short $$$ mods and are not for the adverage owner .. but more geared to those of us who are tech inclined and know these circuits.[disclaimer]
High side temp/pressure checking and air flow has a lot to do with getting high output out of an a/c unit, regardless of what the refrigerant is.. and the main reason manifold condensers are so popular in beefy a/c systems.........