Since I've only played DOA6, I don't really have much to compare it to in terms of difference in mechanics. One thing I would add, however, is an extra area in the Unforgettable stage. There is a segment of glass windows on the upper level of the stage right beside the bar, behind which is a visible corridor. I would make the glass section breakable, allowing fighters to access this corridor.
Oh, and status effects like fire and radiation damage should be a good enough reason to get away from the walls.