I had another guy come out yesterday. He installs Bryant. He said he had two gas air/heat & ac package units. One had a dual fuel heat system, with a heat pump for when temps were above 30 or 35 degres and a gas burner for when they fell below 30 deg. They also said they had a lower end model with a gas furnace heater only to go with the AC. He would sell me that for 5500 installed. (3.5 tons) I asked him for some more info on whether it qualified for the tax credit (he wasn't sure about the lower price unit qualifying). Still waiting to hear back from him.

http://www.bryant.com/products/packaged/index.shtml

Here's another question. A friend of mine told me to make sure the ductwork would be compatible (large enough?) with a new higher efficiency unit. I guess his point was that if a new unit has a more powerful blower and pushes air faster than the duct work area can efficintly move it, I'd just be wasting money buying a higher efficiency unit. It seems to me he's equating high efficiency to high air flow. I don't know if that's a legit relationship.
Are new units equipped with a very high flow and or variable speed fans that might make the existing duct work a cause for concern. All my duct work is in the crawl space. Older, rectangular shape.

FWIW, the guy yesterday told me my existing unit capacity was 4 tons. In his opinion I only needed 3.5 based on looking at my survey floor area. That's what he was quoting to me for 5500. I don't know which of the 3 models....evolution, preferred or legacy.. he was quoting me.

I'd appreciate any comments on that.

I have another call in for a third quote.. tap...tap....tap....tap....