My 2-story 2500 sq.ft house has a 10 yr old Carrier AC/Heating system (outside condenser unit: Model 38YC060, and Inside air handler unit: Model: FA4ANF060; 5 Tons; 10.2 SEER) which controls both first and second floors with one thermostat located on the second floor. The system seems to have a multi-stage Heat Pump. I plan on replacing both systems and an estimate suggested going with a Payne condenser and air handler both with 5 Tons and 13 SEER. Understanding that Payne is made by Carrier, is this a recommended upgrade path? Any thoughts or experiences about Payne systems?