I'm not 100% clear on what you are describing but I'll take a stab. I think you are saying that in order to have a similar 'microzoning' concept, an alternativ

I'm not 100% clear on what you are describing but I'll take a stab. I think you are saying that in order to have a similar 'microzoning' concept, an alternative might be 3 Nests and 3 corresponding compressors. As a retrofit (say, 1 compressor -> 3 compressors [would probably have to ditch the original], ducting changes and 2 additional nests [assuming you already have one]), I would say flair will be more economical. That being said, even if you had a 'large' home with 3 nests and 3 compressors, it is still going to have N rooms corresponding to a single thermostat hence opportunity for efficiency gains and comfort improvement. while flair is a distributed thermostat, it builds on top of Nest in a complementary fashion rather than competing with it.