How is the edge support and usable space for couples?

Solid, with a 9.4 edge score. Edge compression sits in the 2.50 to 4.58 inch range, backed by a foam-encased coil perimeter rather than a bare foam rail. You can sit on the side to dress or sleep right to the border without it caving, so the usable sleeping surface runs the full width. On a queen shared by two, that reinforced edge means each person keeps their full half of the bed.