That seems cheap as I have a lesser system and paid more in NC. I have the seer 15/16 and I don't believe they make a 17 although I could be wrong. Of course my system is a little bigger so maybe the price is pretty similar.

We have a humidifier only on the first floor. The thought is that humidity tends to be the same throughout a house. Well - I am working on this because it is a little dry upstairs. But that is very common practice and I am just picky.

The slave zoning stats read the humidity. The master zoning stat does not display the humidity but I suspect it reads it.

Is a ventilator an air handler?

What are your electric rates, because we share nearly the same climate and a heat pump is a good idea with a quick payback (which of course depends on the price of NG). No question, good insurance for a spike in NG prices. Anyway, if your electric rates are in the $.10 range, then you should upgrade to heat pumps. If you share DC's rates, then maybe stick with what you have. Although no one knows what the future holds.

I'm assuming this includes duct work?

I paid $20k for new construction, 4 ton for first floor and 3 ton upstairs. Heat pumps. NG backup on first floor. Zoning upstairs.