Most definitely Go Around. And this is not A320-specific but applies to all aircraft/all operations.
In our company we have to be stabilized at 500' agl - otherwise GA. Crossing the threshold at 150', especially when heavy and with a wet runway, hardly qualifies.
I have no idea where the 50' above threshold rule derives from but consider that all performance data (speeds, landing distance etc), regardless of being calculated in the FMS or taken from the paper copy AFM, are based on the aircraft crossing at 50', Vref and on the proper profile and in the proper configuration. By not meeting these criteria you are in effect out of the envelope, maybe too far out, and that can come with a hefty price tag and even with a capital punishment not only for you but for the rest of the crew and the passengers as well.
So yes, I would consider it mandatory. Check your AFM and in the performance section, in this case landing, and it should state how to achieve the speeds and distances supplied by the charts/tables/FMS/... Most likely 50', Vref over threshold, throttles to idle over threshold, etc etc.
Last edited by firefish; 18th November 2010 at 11:28.