just FYI: I just built a Love Pedal Eternity for a customer with a SAG pot. I was really surprised by how much this one little thing gives you so much tonal variety. It tended to really smooth out the tone, while reducing volume (of course).
I think a great design would be to have a SAG volume for rhythm settings, and add a bypass stomp for lead solos.
Adding SAG to a single pedal is very easy, just use a 10k pot a trim some of the DC+ before it hits the effect circuit.
Does anyone have any circuits that they think work especially well with SAG?
Take your DC input jack and tie positive to lug 3 of a 10k pot. Tie lugs 1 & 2 together and also connect lug 1 to the DC+ input of your circuit. Nothing changes on ground, and the pot is not connected to it. This is the "one pedal" method.
You have to be careful when you use SAG that you don't drop the DCV for several pedals. For example, if you put the SAG in a separate box then don't put it in front of a chain of DC adapters.
Also: FYI, I tried the voltage divider one with 2.2k resistor but it is much more complicated, while the approach above works great and is easy.