Thanks for the informative responses.
I'd like to point out that I am not criticising he crew for not "getting on with it" and ignoring the limitations. My main critisism is with the aircraft itself in that for something whose "bread and butter" is regional operations it should be able to handle a wide variety of situations.
The only thing I will critisise the crew for is not telling us the luggage had been offloaded. If I knew that was happening I would probably have got off and taken the train instead. That way I'd have been able to work and not lost a dyas work.
Coffin Corner - The captain definatley said overweigh for takeoff.
mathers_wales_uk - I'd be surprised if they don't know with a high degree of certainty how may bags will be on a flight. After all most pax book bags in advance to avoid the high charges at the airport.
WRT to seats the BE online check-in engine seems to be quite good at distributing the load. It only makes available certain seats for pre-allocation and seems to allocate most seats at the rear.