Hi
I'm using the MusicomLab EFX MkIII with all 4 Eventide boxes as well.
I have not tried to setup a footswitch via MIDI as I have not found this to be necessary, so I can't comment on that. But I have tried an EXP pedal and I can share my experience.
The problem is that the EFX can only transmit CC messages for the expression pedal OVER 1 MIDI channel. Therefore you cannot use it to control multiple Eventide Pedals directly. If you could select multiple, or OMNI on the EFX that would solve all problems, but you can't.
There is a workaround where you can transmit the messages to one of the Eventide units, and then use that to XMT to the others. But here I'm pretty sure that each pedal can only transmit to a single channel also, so you might have a difficult time here. This also requires you to set the MIDI type to XMT rather than THRU, which means you can't receive other MIDI message (e.g Program change, tap tempo) through the chain, without the use of a MIDI merger at between each pedal.
In the end, I decided that this was too much of a hassle to worry about, so I'm currently using the EXP pedal thought the Pitchfactor, where it is most useful.
I'd be interested to hear if you find a solution! Hope this makes sense as I'm typing very quickly as I have to go somewhere 🙂
