I am considering updating a 20 year old Goodman single stage furnace to a high efficiency Trane or Rheem furnace. I have a two story 2600 sq ft house in southeastern Wisconsin with new windows and R-30 insulation. In looking at high efficiency furnaces, I can get either a two stage or modulating furnace. I have heard that modulating furnaces sometimes do not heat the upper rooms as well at the lower heat settings which negates some of the advantages. I have heard the two stage furnaces do not have the problem. Is this true? How can I find out without a costly install only to discover my upper floors do not have enough heat? Any thoughts on Rheem vs. Trane?