Pittsburgh note
For Pittsburgh winters, also ask about capacity at low outdoor temperatures — HSPF2 alone does not describe design-day heat when temperatures drop into the teens.
Efficiency versus capacity
A heat pump can look efficient on paper and still leave a third floor cold if low-ambient capacity and duct delivery were never checked. Ask for both the rating and the winter capacity plan.
Where dual fuel enters
When the house still wants strong design-day heat and gas service already exists, dual fuel can preserve comfort while letting the heat pump carry milder weather efficiently.