I live in Southeast Texas and need to replace my 5 ton heat pump. I have quotes on a Lennox, Bryant, and American Standard. The prices are comparable. The units I have been quoted seem to be the upper units of the lower series of all three brands. Price of the upper series are out of the question. There seems to be a significant jump in the prices to move up to the middle series. It seems that if I have a p&l warranty, the difference would be the efficiency. My question, is the additional cost worth the savings by moving to the lower or middle end of the mid range units? Will the additional cost be recouped in the 10 to 15 years? Also, is my assumption about life or maintenance of the unit with having a p&l warranty correct.