I narrowed down my bids on two HP systems: Carrier Performance 38YXA048 with variable speed air handler and the Infinity system of the same size (38YDB/FE4AN). I've heard alot of good things about the premium Infinity system but its EER is lower than the standard system and does not qualify for our energy company rebate. SEER and HSPF are slightly higher 14.5 vs 14.1 and 9 vs 8.6 for the Infinity but our high summer temps. (often >100F) make me think EER is more important. Considering these facts, is the Infinity worth the $600 premium?