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The simplest question can have the most complex answer at times.  I'll try to help.  Variable speed systems have some advantages over single stage or single speed systems.  For Florida I would say the best benefit is that it allows the system to be optimized for dehumidification in cooling.  The fan slows down and the cooling coil gets colder and pulls more moisture from the air.  This adds to comfort as well as reducing the risk of mold growth in the conditioned part of the home.  If any heat pump system is properly sized for cooling it will almost certainly provide all the heat you need without strip heat to supplement.  There is another choice which is 2-stage or 2-speed.  In this case the high speed is reserved for the dog days and the unit will run on low on cooler days and in the evening.  This may be a good choice.  Reputable manufacturers will warranty their compressors for 10 years and I recommend Carrier, Trane and York as top brands.  Be sure you save your purchase documents and register the installation.
The most important thing I can add is that it's true that you get what you pay for.  If you look for the lowest cost you get not only the lowest cost equipment but also a contractor perhaps less trained, less equipped and willing to cut corners that will affect you for years.  It is my belief that when you see bad reviews it is more likely the contractor earning the score and not the equipment.  So I recommend you pick your contractor first and allow them to customize the system to your needs.