I picked up an OX switch for my Pictchfactor. Basically a 2 switch aux pedal with input for a separate 3rd switch (intended for tap tempo but could be assigned to any aux switch setting). Very low profile, adds less than an inch to the depth of the PF. Since I normally just use 2 aux switch settings, this works out well and saves enough room on my board that I am able to add my Wahoo to the mix.
The Wahoo expression pedal sends midi expression out

so no need for a separate expression pedal. Problem is, it needs a USB/midi converter which I don't have

so I will have to make additional investment (will probably pick up the Disaster Area gHOST converter). Regardless of the expression pedal capability, the Wahoo and the Pitchfactor are a pretty fun combination.
The OX is a pretty cool device for those interested.
www.barn3.com