Essentially, summed up...
There are some idiot dog owners who let their dogs run about unhindered;
There are some good dog owners who keep their dogs under control;
There are some idiot cyclists who ride stupidly around dogs;
There are some good cyclists who ride sensibly around dogs.
I think that about covers it.
One thing I would say, as a former dog owner whose dog walked everywhere off the lead (Border Collies, best dogs in the world), I would make a point of grabbing his collar in case of potential conflict, or if too far away would shout on him to stop and lie down so the person approaching knew he was under control (remember, while you may know the dog is under control, others may not, and apart from anything else there are people out there who are scared of dogs and one person's bounding, joyful, tailwag is another's bitey nightmare).
The only other thing I'd say is in relation to this:
"No I wouldn't trust my trained dog not to engage in erratic behaviour now and again. Similarly I wouldn't trust most toddlers, wild animals, joggers, cyclists, motorists not to engage in erratic behaviour now and again. My point is it is useful to anticipate behaviour like this and moderate your cycling accordingly"
Absolutely. Cyclists definitely should moderate their cycling accordingly, and equally, in a shared space should not dog owners moderate their dog walking accordingly? Two way street.
I have no problem with dogs generally (perhaps being a former owner helps in this regard) - there's a lady walks her lovely mongrel and Rottweiler on the the Innocent every morning, and when I go that way I make sure it's clear I've stopped pedalling and am covering the brakes/have slowed down, she has one of the dogs on a lead already, and calls the other to her. Seems to work. The world keeps turning.
"... which is only assuredly the case if a dog is dead"
Hints at a slightly prejudiced view of canines...