Old System Blew Cooler Air
Yes it did. Older system design specifications called for the indoor coil to cool to 40°, modern systems call for a 50° coil. Why? Modern manufacturing allows for the coils to absorb heat from the indoor air more efficiently. This allowed a 10° warmer coil to do the same work in BTUs. In turn, this made it so the compressor did not have to work as hard. A modern high efficiency compressor can now produce the same BTUs as a 1980s compressor while using 1/2 the electricity. Note: airflow from your vents should never blow directly on you (or when the A/C cycles off, you will feel hot and miserable), but instead should be aimed to cool the air in the whole room.
Old System Drain Didn’t Plug
Florida has algae, not only in the water, but in the soil. Fertilizing can feed the algae and make it worse. A 1972 Florida soil survey found 72 species of algae, with the 5 most common found in every soil sample. Copper sulfate is a granulated algaecide many have used to treat pond algae. A/C coils used to be manufactured from copper piping (most of which is now aluminium). The copper would very slowly decay into the condensate water and run out the drain line, controlling algae growth. Current best practices call for frequent wet vacuuming for the drainline. (monthly w/filter change) Another option is to upsize your condensate drainline from 3/4″ to 1″ piping.
Old System Didn’t Run This Much
True, it didn’t, and you want that. (see *). The reason the heat is so unbearable in Florida is the high humidity. We are dealing with two types of heat, heat of the air and the heat of the moisture in the air. Modern A/C systems can run at reduced capacity and slower airflow which allows the air lingering in contact with the cold coil for a better chance to turn humidity into water to be drained outside. These systems run at greatly reduced wattage for extended periods to remove that moisture from the air.
*Assuming the system is the correct size for the space, the ductwork is designed for correct airflow, and the system is running up to specs.