Anyone tried the Darkglass Midi Footswitch with the QC? I saw below youtube video. 5 switches tempted me to use it on stage for 5 scene options in front of me (apart from 8 stomp switches of QC).
And since both brands has same owner I guess the compatibility will be at it’s finest level 
I haven’t used one, and I’m not sure when it was introduced, but Darkglass was sold to Korg quite a while ago.
I’m sure the compatibility is fine, just about any midi controller pedal will work well with the QC.
Just bought one myself, in hopes of more flexibility or additional choices in one scene. Literally got it yesterday.
You can get 10 buttons for $10 less PaintAudio MIDI Captain Foot Controller (BLUE)