It is not about the equipment! No variable-speed, zone-control system with learning thermostat will insure occupant comfort or protect indoor air quality.
Homes today are so well insulated that the distribution of air is no longer a function of the heating/cooling requirements, it is the direct function of the volume and architecture of space.
Healthy IAQ depends upon much more airflow than the heating/cooling equipment will need.
The volume and design of each room requires a certain amount of air delivered at a set velocity.
Variable airflow systems violate that basic engineering principal and thus fail to provide comfort and humidity control.
The ADS must be designed into the home, fully coordinated aesthetically, with all structural elements and the pressure/thermal boundary.
A healthy, comfortable home cannot be assured by allowing a mechanical contractor to improvise the installation during construction.