What is your opinion on using a unit with a SEER rating of 17 vs a SEER 13 or 14 in an area such as Phoenix with a mild winter and blasting hot summer? I'm a homeowner looking at a system with dual compressors and two-stage cooling / 3-stage heating rated at SEER 17.9... is that overdoing it? My neighbors all seem to have a single compressor SEER 12 - 14.