What Jonathan suggests "3m/s^2 acceleration (reasonably snappy for a machine this size)" should be quite snappy.

I could judge only from my lazy small machine and my first build which was for a friend, where i left the acceleration to 0.8m/s^2 cause after that it started to seem a bit dangerous.

Imagining that beast now to move the gantry from one end to other for 1 sec, thats would be quite a view. But as i understand it, the acceleration has more to do with corners, circles and so, than moving the gantry with tremendous speed from one side of the table to the other. Cause at the end i control the machine paths so generally i always strive to make them perfect, without wasted movement.