Sub 'n Up + OD Which One?

In a perfect world my Sub 'n Up would already have a "grit" option. But, alas, I must toil to find the best OD for my pedal board. I really like the OC-3 Drive setting but it doesn't allow you to use it in the Poly mode.

So, I'm wondering, does anyone here actually know for sure where the drive in OC-3 comes from? Blues Driver? OD-1, 2 or 3? It doesn't have to be the exact pedal but it would help me make a decision. Thanks.

 

Writing this thread started me thinking and that lead to me to the Boss ODB-3, which should do exactly what I'm looking for. What I hadn't considered was the Red Witch Factotum:
What a cool pedal and I can get one new for ~165 bucks. Of course, Andy can sell ice water to an Eskimo, so I'm wondering, any real world users out there?