I certainly used that Granny gear at Mohican. It let me ride up steep hills past folks walking their bikes at my part of the pack. It can be a bit wobbly at low speeds, but the bike doesn't veer much even if the bars wobble compared to an upright.
I would use the granny off road and not worry about the wobble. You're right that the bike as a whole wasn't moving off line much. I just wasn't prepared to trust myself with cars coming up behind me. And I didn't want to give them an excuse to cuss me out.
The bottom end is probably lower than what I have on the Greenspeed.
Agreed, wobbling is right out on roads beside cars.