TOGA vs firewall
I fly 330's. Toga is throttles full forward, with max thrust still controlled by fadec's, and is not above max "rated" thrust.
In DC10 and 737's that I flew previosly, Go Around thrust was a setting slightly below throttles full forward, and at a position appropriate for max "rated" thrust. If I pushed the throttles all the way forward, i.e. firewall (which used to be a proper SOP term in some airlines), I would use max available thrust, which would possibly be above max rated thrust. This could lead to a complete failure of the engine/s if unlucky, and most surely would lead to some damage or life-time degradation, but could be used in a situation where the only other alternative was ground impact.
Is this not the case in B747-400? What about B777?
As a side-note, it's still possible to use "firewall thrust" in an airbus, but selecting N1 mode and set the levers to the Toga position regardless of outside atmospheric conditions. It'll just take a few seconds longer than on a classic steam driven airplane.