Heat Pump is for Southern Areas with Mild Winter!

Heat pump is ideal for southern areas with mild winter since it stops working when temperature reaches around freezing (around 35F).  It has gas heating for emergency  or when temperature is too low.  If you live in a very cold area then most of time it's still using gas.  I am windering which brand of heat pump can not heat?  Also, slow heat has an advantage which is that it's mild and not too dry comparing to gas heating.  The name brands are Trane, Carrier (via Sears), Linox, etc.  Trane is famous for commercial.  But these days, all brads are using compressors from a few manufactures and brand is not as important as the technician.  Find a good technician is much more important than a name brand.