I forgot to add that in my application the accel and max v will never change only the direction and distance therefore the ramp array will never need recalculating , for "short" moves i just reduce the number of elements played out. the pid tolerance seems pretty accommodating.
I want no overshoot no stalling and no hunting +- 4 counts is accurate enough . its controlling the really stiff and jerky air slide on the pid controlled wood heater in the lounge (its a matter of principle)