Here is the deal that the contractors may be looking at.
where is the furnace and evap coil going to be located?
in a closet, basement, attic?
How much room is required for the install? Will it be up flow, down flow, horizontal? Then the contractor will look at what setup will meet the tax credit for the hybrid heat or heat pump. What is the Evaporator they are going to be installing?
We have to know this for the capacity of the heat pump in high and low speed for cooling and heating. They can easily do a manual j and then they can easily come up with two different results too. What if your home needs 2.5 tons? Your square footage is sort of in that range. The first guy may think the 2 ton will work just fine because you may be on the border line for cooling capacity and the other one may think since this is a two speed system and Infinity does not make half ton sizes and it is recommended by carrier to go up in size since the A/C will also modulate in low speed most of the time. Your furnace also modulates
The 100-20 ranges from low 38,000, med 61,000, to high 94,000 btu
and will probably modulate on the low speed or medium speed most of the time. The 80-14 ranges from 30,000, 49,000 to 74,000 btu respectively. You also have hybrid heat so the heat pump will do the work on mild cold days plus it can work with the gas for back up heat. So you may not need a larger capacity. back to the evaporator coil.
Depending on the coil since most coils do not sit evenly on a 80-14 many install companies may use an 80-20 the only reason one may not use an 80-20 if it is in a horizontal application and because they have to get the furnace in the attic. The 80-14 is much more installer friendly and can fit through rafters nicely. It would really depend on the load calc and where this is going to be installed in which way I would go. based on heat pump criteria,
The installer with the 3 ton, has to use a 100-20 for the tax credit while the 2 ton guy can use a smaller furnace to meet the tax credit. | 
