I'm trying to decide between 5-ton split units: Lennox AC13 VS with G60 gas furnace and the top of the line XC21 VS with gas furnace. Is it worth paying the extra $$ for the XC21 in regards to efficiency? With the 5ton will the XC net around 16SEER or so? Also, is there a big quailty difference b/t the two product lines?
PS- I live in the Phoenix area; I know it's a dry heat!!!