You need FLStat to find the correct entry for the shiparch ini, from then it is pure calculation!
The reactiveness or better put the turn acceleration is
steering torque / rotation Inertia
-calculated for each axis
It gives you "jumpiness" if too high, or a non sluggish behaviour if only "high" , or a slug like turning if it is very low.
Practically, one would have to calculate how much time it needs to get to a ships max turn speed to see how much it really counts for each ship- also it depends on how you fly that thing ...so it might matter big time or not so much
Edit: also- with these calculations: the z-axis is useless, don't let anyone tell you otherwise