Just to throw in here. I just rehoused a Digitech FS3X aux switch and "modded" it with two outputs. All I did was add an extra TRS out and connect it to the existing TRS out. All works great. Simultaneous control of two factor pedals.

I ended up buying a Mission 25k dual output exp pedal.

Now I have one aux switch and one exp pedal for two factors. Very happy.