I know what you mean about dobes howling, but that only do it in a pack formation.
The other thing with dobes is that they do not put up with stupidity as they are very intelligent dogs, and if they think that they can get an extra inch then they will try for the whole damn mile.
Concern the rottie bark. If they are barking then your ok, it's when they go quiet and smile at you that you have to worry. LOL