Comparing high-AFUE' furnace (e.g.: Tempstar VS90, two stage, variable blower) and 14 SEER A/C. Tempstar vs. Carrier. I know both are owned by the same parent company. I have heard they use many of the same parts and, in fact, many internal parts on a Tempstar have the Carrier name on them (true?). That said, other than a low four figure price difference for the package, is there much difference? Any of the pros here have any concern or praise for Tempstar, presuming proper sizing and a quality, professional installation comes with it? Thanks!!