While I haven't quite figured out how to grow them real large, I do seem to be able to grow more than enough to sustain us through the winter. (I'll see if the wife can assist with posting a pic or two when she gets home.)
I think the ones I harvested last night are of a yellow variety, not real big like Idaho size, and not dark like the russets. Basically I just set a few aside from whatever we've occasionally bought at the store and come Spring time, get them in the ground when they're starting to root out. The largest of these is probably 4" by 2" but most are about soup/stew size, 2" round.
Still have russets and somekind of red potatos in the ground and in a really big pot, but they're not quite ready to harvest just yet. Will post pics when they're ready too.
Badger