IMHO if you have a tight system, and are looking for the optimum
performance out of your AC stay with what the manufacture designed it to
work the best with.
R-12
You can over condense, hang a 55 Packard dryer on the system, or even
mount a 69 Caddy Fridgidare compressor on the engine, and you'll never
enjoy the same temps out of the vent's with R-134.

And it also does have a tendency to leak through the older hoses and
fittings.

Not unless you choose to replace all the hoses, o-rings and fittings
along with the condenser.

134 is not a wise selection for Florida temps, and humidity.

RC