The variation of this circuit that surprised me is the Tchula circuit.
The whole concept really made no sense to me... in one mode you have no control whatsoever, no volume control, no gain control, you just switch it on and it does what it does... take it or leave it.
The other footswitch enables a gain control.
Quirky as hell, I expected to be extremely underwhelmed, but man, it sounds fantastic in either mode and actually does "work" .