A couple of things you might want to know if you are considering the IK Multimedia BlueBoard. This information comes from IK’s video about the BlueBoard, answers they provided in the comments to that video, and playing with the app.
The BlueBoard is primarily in either program change or control change mode. So, you can not use the foot-switches to switch presets while also using an expression pedal to control volume, wah, etc.
There is a mode that can do program changes via the bank switching feature while otherwise being in control change mode. Bank switching, by the way, is done by holding down the A or B foot-switches.
Also, you can not use two BlueBoards with one iOS device. So dedicating one to program change and one to control change is not an option.
Overall, this is pretty disappointing. Since my Griffin StudioConnect has MIDI, I’m going to be looking into conventional MIDI foot-controllers. Still, the BlueBoard would be useful even with its limitations.