[Hammer]

I'm in the HVAC biz and we don't do any new home construction beyond occasional room additions and other types of remodeling with custon builders. But we do a lot of service work on newer homes and find too often that the HVAC systems are always the area that is used to cut corners to allow for other upgraded cosmetics to keep overall cost down.
The problems we see are in 2 story housing is that the second floor areas are not adequatly (sp) feed with air flow, and therefore, they are sometimes 8 to 10 degrees warmer in the summer than the first floor. That is something I could'nt stand at night.
Don't let them skimp on the system and it's design. Zoning the first and second floor is an option with seperate temp control.
Bryant/Carrier have a very nice zoning setup with the Evolution control, but this is usually the higher end system and would need seperate duct systems for the 2 seperate zones.

Good luck