Hi, I can answer my own question now, having bought, tried and sent the Electro Harmonix Expression pedal back! Hope this is of use to someone else.
It doesn't work: it induces an effect that is not the one listed, and doesn't return the actuated effect back to original repsonse. This is despite ensuring calibration of E-H pedal, adjusting range setting, powering up the Eventide with the pedal plugged in, and trying the 'mono' cable (which is supposed to make it act as a voltage controller). All tests…nix. Doesn't work 🙁 Shame, it is a lovely expression pedal, well made & thought out, and nicely designed. Just doesn't work with Eventide stomp-boxes. Am now trying to source a recommended Ernie Ball 25Kohm pedal. David
