rdnzl:

Here is the feedback: not great interop I'm afraid.

The pedal acts like a volume pedal (goes from 0 to 100 to 0 when going from heel to toe).

And the footswitch well, not sure what it does… on click and it does do something, but then as many other clicks, nothing, the pedal does not react 

Sorry about that. We tested some different combinations of expression pedals with aux switches. We know that the combinations mentioned in this pdf worked:

http://www.eventide.com/~/media/Files/Audio%20Support/H9/Everyone/H9_Y_lead.ashx