Progress,  page 96
We selected a system that provided two heating/cooling units, one for each end of the house, but
even so I was concerned that the master bedroom was too isolated for proper balance of the air
flow.  The solution was to make a separate run to the master bedroom with an intelligent
controller that could automatically redirect air flow as desired.  That required more ductwork,
but what the heck.  One of these runs goes to the kitchen/dining area, and the other goes to the
master bedroom.
Most of the ductwork was rigid (less air resistance), but usually the last few feet of each run was
flexible.