I don't know about 250Hz but at 1000Hz there is no offset of weighting requirements. That is to say, it doesn't matter wether it's A weighted, linear, etc, the response leve is the same.
Accelerometer calibrators often operate at 159.2 Hz because that is equivalent to 1000 rad/sec rotational frequency. (159.2*2*PI = 1000)
At this rotational frequency, acceleration, velocity, and displacement are all related to each other by a factor of 1000.
For example, if a calibrator produces an acceleration level of 10 m/s^2, it will also have a velocity level of 10 mm/s and a displacement of 10 micro-m.