My point was that, when you have to "teach" the WST-EC on high travel rates, the WST will set the gains to those travels and saves those. When you then reduce those travel settings in your transmitter, irrespective of how you achieve this, with the servo travel or dual rate settings, the WST still retains the saved stabilisation gains and may overcompensate as a result. Hence my suggestion to reduce those gains with the sensitivity channel on your Tx in that case.
Unless of course Frank is right in his assumption that the WST is "smart", and adjusts the gains as a result of your flying behaviour.
And as Frank stated correctly, the gains are highest at neutral control input, and reduce to zero at full deflection (I tested that on the bench). So they will not reduce to zero when you are flying with your D/R set to low rate, and will still compensate even when you have full stick deflection! I guess this may feel as "sloggish" behaviour, since the WST is fighting your control input. Remember that the WST has no way of knowing how your control input is put together from servo travel settings, dual rate or expo, all it is seeing is a channel output value.