X2. We don't know what "total" means in this case -- was it adjusted based on SHR?
Keith,did you tell him your typical set points in the summer/winter? You're on the right track, but you do not want to oversize 2-stage units. Low stage of a 4 ton dual stage scroll unit would cover your total load, which defeats the purpose. I would clarify why he is suggesting a 4 ton unit? A lot of times the existing ductwork isn't capable of moving the required airflow. A variable speed motor will have a greater ability to move the air against greater external pressure, but the ductwork still needs to be fixed or the system will be loud and energy inefficient. You want to make sure that the ductwork is looked over and any changes needed be made. Big difference between a 3 ton and a 4 ton system.
What size is the existing system?
The system is sorta mismatched I'm told. 3-ton condenser, 4-ton coil. It has an old Allstyle coil they say with one huge return duct coming into the furnace with a 16" opening I believe.