I have found a qualified installer and he has quoted me prices for Lennox and Amana which are pretty comperable. I 'm looking at the high end 4 ton heat pumps that have the two stage compressors (Amana RSG Ultron 16 or a Lennox HPX 19) with a variable speed 80% furnace (Amana AMV or a Lennox G60V). Any advice on which way to go?