So - we went with the Amana system... couldn't be happier.
To answer some of the questions... They put in larger ductwork to half of the house for the slightly larger system (previous was 3.5). They also installed a communicating stat made by white rodgers (branded ComfortNet). The biggest difference we've seen is how much quieter the system is and how much more dry our house is. MUCH more dry... it was a cold steambath before. We do have large windows that go down to almost the floor, a skylight, and 10' ceilings (higher in some places).The Central FL sun and humidity did a number on the previous system... not to mention, the previous 14 y/o air handler that came with the new construction was sucking air from our walls... had a small hole a few weeks ago in the dry wall that was whistling... a quick seal of the box under the handler took care of that.