Of course it would happen after I had typed reams :) So here is the actual update. My son, Milo and I went and visited all the better pet stores in the area and talked to the owners about Orijen, Fromm, and others. Funnily, they all hesitated to recommend these two brands and kept steering me towards brands that I knew were not as good! Volume incentives?
Anyway, at the last store, a small, poky little place recommended by a fellow morning dog walker, the owner listened to my tale of woe, and said understandingly "Labradoodle with sensitive stomach? I have just the thing for you." and produced a bag of Acana. Since Karen had mentioned it, I asked him more about it, and he said the higher protein of the Orijen sometimes itself created soft poops, and a lot of his labradoodle owning customers had good results with Acana.
We bought a small sample, opened it right there, and Milo who has to be coaxed into eating his Prairie kibble by adding yogurt or pumpkin, wolfed it down enthusiastically as though it was a liver treat!
So feeling hopeful that this is a step in the right direction, and many, many thanks for all the advice you all have given us.
Poop status report to follow :)