Here's one I run into often,
Customer is adding air to an existing MH furnace, considering an outside Pkge unit. The blower in the MH (let's say Double Wide) is a 1/4 horse power. Would you add a coil and condenser and leave the machine at 13 seer? Or, would one consider installing an outside ground Package unit to try and reach 14+ Seer?
The benefit of an outside unit would be less noise, more space and a better filtrations system, plus a higher seer.