I have been quoted an Amana asx16 with matching 96% 100k btu furnace backup. Will also have all new ducts installed. Is this a decent system? Do I need a 5 ton? I currently have a 3 ton 10 seer and it cant keep up at all. My electric here is 6 cents Per kw. here in ky. It can be 95 and can get to 20 sometimes. The home is 2500 sq ft, and the ducts are from the 60's when the home was built. I have had blown insulation in the attic and new windows installed. Is this the best route to go?