The airflow seems decent but definitely not as strong as closer to the A/C. I haven't checked the temps at the vents yet and don't have a real good thermometer to do this with consistent accurate readings.

The master bedroom has a 12x12 return vent in it and the main return is just outside the master bedroom door. There is enough suction to pull the door closed. The kids bedrooms just have jump returns to a vent in the hallway. If you leave their doors cracked you can feel the air flowing through towards the main return. Not sure if this is helpful info or not.