Don't Portuguese Water Dogs already fulfill the function of Labrodoodles? They don't shed, they fetch, and they swim. I don't know if they make good guide dogs, though. When I worked with a guide dog outfit in France, I saw mostly goldens and German shepherds.

Mutts can make fine guide dogs, drug dogs, cadaver dogs, bomb dogs, too. But you can't breed them to be so, some just have the right stuff, and there's no easy money in pound dogs like there is in breeding operations.