Coming from a cat point of view, canned foods can have lower carbohydrate contents than dry foods because they don't require it to keep form (not that they always do, plenty of canned foods are just as carb heavy as dry) and they have added moisture which is more important for cats than dogs because cats don't drink unless they are running seriously low on water and are dehydrated, dogs usually drink plenty. So I think wet is great, possibly better than dry especially if you are buying the brands that are 95% meat or close to that (but still "complete and balanced").
The biggest downside to wet is cost. The teeth thing is a myth, I mean think about it logically. Kibble is a crunchy carby food like a biscotti and wet food is soft and wet like stew or applesauce (okay maybe not the best comparisons), what's going to stick to your teeth more?
We have always mixed wet and dry food together, enough so that all of the kibble gets some on it.
As for when to go from puppy to adult, I'd do around 8 months to a year, but it depends on the breed of dog I think (well the adult size). But a lot of the higher quality foods are all life stage foods.