So much bad info in this thread. Almost all new construction already uses forced air heat pump systems for energy cost reasons. Supplemental gas (or electric) heat is only turned on by the unit when it's too cold for the heat pump to function well. All this change means is that units with supplemental electric heat will be chosen over those with gas supplemental heat.

Additionally the compressors in these systems use far less than 50 amps, typically typically around 12 for a 3 ton unit.

The type of system you described is generally used for old construction where adding ducts is impractical. Because it's used for a special situation it will of course be more costly.