The Dash8-100 (depending upon mod status) has a statement in the AFM that take-off's should be with Yaw Damper OFF (unless take-off is Flap 5 at a weight greater than 14,400 kg). I did once know the reason for this but cant recall. I think it has something to do with V1/Controllability etc. Much like V1 min is higher when operating on narrow runways. Why is a good question!!!
Not sure what "speed schedule" you are referring to for calculating take-off speeds, unless it is a company document. In which case could be basing the data on weights above 14,400kg to permit Yaw Damper ON take-offs??