1) Is there any good, hard data on comparing the efficiency of a two-stage 15 SEER vs. a standard single-stage 15 SEER units? I recognize that heat load will determine how often the 2nd stage is used but I would expect at least some data such as "Assuming 80%/20% 1st/2nd stage operation the SEER is xx). I'm surprised too see the cost savings I got from my dealer didn't include this. This looked like it came from Bryant and was based on the second stage always being used.
2) Are there reliability issues with these units compared to single-stage? The exact unit I'm considering is the Bryant 187ANA (2-stage reciprocating) vs. the 165ANA (single-stage scroll). From what I read here the 2-stage reciprocating units sounds like it will have a smaller first stage output than the two-stage scroll unit (180A).