Tightslot #24 : The Cranfield (and other) research found that evac flow rate at the overwing exits was actually speeded up in some cases when seats were present in the exit row, as opposed to when removed partially or fully - I know, this sounds bizarre.
This is intended to be a serious response : I believe this has to do with the natural hearding instinct, there are studies which indicate that persons exiting an area through a constriction (door, window etc.) in a panic situation do so in bursts and not constantly. This is a paper based on a study using mice
here, and reading this, my conclusion is that having the seats in the exit row disrupts this hearding behaviour - encouraging queueing, leading to a more consistent flow rate through the exit portal.
On a similar line, I remember watching a study of "exiting a room in a panic situation through double doors", and placing a barrier in line with the centre of the exit portal, significantly increased the throughput.