When I think of Pinion, I just automatically think of the 18 speed, as if I got one that is what I would want. When I first got my Rohloff, I wished the gears were closer together, as they are on my other bikes with derailleurs. But I got used to the slightly wider gearing pretty soon. But the 12 speed pinion is wider than the Rohloff, wide enough that I would be disappointed.
My Tandem has the 26" wheels just like my rohloff single. The lowest gear on the Tandem is a 24" gear. I was used to this when I bought the Rohloff so the gear jumps on the Rohloff never felt to large to me. The Pinion 18 speed is the one I would get if I were to purchase another bike. I do agree with you on this. more range and smaller gear jumps sounds good.