Cornish isn't well known these days it seems; and he never did mass market, even less than Roger Mayer...which is a shame. There are reasons why pros went to both of them for gear back in the day.
I think these are what many players are chasing but with Klons, Timmys, OCD, Angry Charlie, AnalogMan, etc., they're not as common or well known.
The SS-3 and G-2 alone are great, stacking them is great too. Which is why you're making one for yourself!
You need someone with the chops to demo (which isn't me) this duplex pedal for you....I think they'd sell more once people hear it and learn about it.