While I don't necessarily advocate taking off deliberately overweight...
I've seen people getting excited seeing a couple of kg's over MTOW on the a/c's weight display and doing some weird stuff, riding the brakes included. (BTW, has anyone mentioned additional FOD risk due to increased thrust during taxi?)
Now, the airplane's weight display (at least on the type I fly) calculates the gross weight by adding actual fuel weight to the ZFW entered into the MCDU. This displayed gross weight goes up and down as the fuel is sloshing around during taxi and its accuracy is limited. I think when legalities are concerned, the Loadsheet should be the basis of determining the TOW.
On one such occasion I have seen the CA burning the fuel during taxi. Then, when we stopped at the HP the ECAM weight indication stabilized and we ended up showing 2000lbs below MTOW...
