Personally, I'd rather take my chances being trampled than being slow to get off the plane (because of being far from an exit row). The second situation can be fatal!
JPT,
Not to belabor the point, but big people in MOST aisle seats would be blocking just one or two other passengers in an emergency. In an exit row, an unconscious large person could be blocking everybody!
The whole exit-row thing always seems kind of silly to me, but I've never experienced a serious emergency, so what do I know? I sit there a lot and always agree to help out if necessary.
Bruce