BTW, as the hub gears up, this reduces the torque through the gear train.
I'm not sure that makes much of a difference, because any of the three epicyclic gear stages could be taking power directly from the driver without gearing up (in second, third and fourth gear), they all see the same amount of input torque.
I found the 30-tooth crank on SA's website, good to hear it's worked fine for you, I'll probably go with about the same ratio. I've got a 28-tooth chainring kicking around somewhere, and a crank to mount it to.