Ratherbeflying,
You' re right. Reversers on the ground (the only time they should be used), since engines are above the wheels, will produce a pitch-up moment.
Edited ----------
Well, I guess we were wrong. Thrust reverser moment depends on wether the thrust line is above/below the acft CG.
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Besides asymetric thrust, pitch up moment is probably a reason not to use full reverse on highly mounted MD80's engines on contaminated runways since this tends to lighten the nose wheel.
Some poster said the nose wheel is light on 747's. It must be taken into account that when heavy braking is applied, the load on the nose wheel increases substantially. If you are able to rotate the airplane at 80kts during the take off roll I am not so sure you could during a heavy breaking deceleration. Has this been "flight" tested in the first place?
About the better tricycle directional stability, the pull coming from the tail's aerodynamic braking tends to make the acft more directionally stable.
The autobrake puts whatever braking it takes to achieve a decelaration rate as long as the wheels keep spinning otherwise anti-skid prevails. That is why it is important to prevent the wheels from locking.
I agree with one of the posters that no smart theory can help you when you are in the cockpit, so maybe some test should be made and results discussed.
Just my 2 cents
