I have to echo a few sentiments:
-I don't think of any of the breeds being discussed as "easy" in the sense that it's being used. Some individuals are but in general the basic make up of these breeds means that "go anywhere, do anything" dogs are created with lots of hard work on top of correct genetics. But they all tend to not be simple, straight-forward dogs and are instead rather complicated, at least IME. If I were looking for a "break" after having a difficult or demanding dog, I would not be looking for a Mal, Dutch, or GSD. I really love this type of dog but easy they are not. I'm not at all saying "You can't handle one" because I'm sure you can, I just don't know if that's what you're looking for right now.
-I can't see a dog from those breeds being suitable for repeated reactive dog exposure, for the reasons other have said. They're quite "moldable" IME and could easily become reactive themselves after repeated exposures to a dog that's threatening or antagonizing them. They're designed to respond accordingly to threats, not look the other way. I think in general they're too responsive and confrontational for reactive dog work.
-Public access can be challenging depending on the dog's temperament and the idiocy levels of the public at any given time, as others have said. :lol-sign: IME the vast majority of the working shepherd types are just fine with out in public with neutral strangers, but that's assuming neutrality and respect from the strangers... which can be a lot to ask these days. Most people have an idea of what dogs "should be" and act on it, and these dogs (and others too, obviously, but especially these dogs) don't always fit into that.
Also, on a different note, I think it's extremely obvious that mouthing/biting in an adult dog and mouthing/biting in a 7 week old puppy are not comparable. That seems obvious to me, but since the comparison was made, apparently it's not? I have little comment on the issue; I would be appalled at an adult dog of any breed doing that and I admit that dog would not exactly be seeing my happy face or my patient side right there and then, but I also haven't trained every dog and I certainly know how these dogs in particular can be. I still get bit sometimes, it happens, mostly sloppy targeting but sometimes plain frustration or stupidity (mouth first, brain later... or never) on the dog's part. I'm not exactly lax about it or very forgiving of bites that don't come from honest targeting error, and I admit I think that plays a part in keeping those events relatively isolated, but like I said, I haven't trained every dog in every situation.
My last thought is that if I was personally looking for a reactive dog helper, I'd probably look at adults and be looking the right individual, with breed not really being a big part of my consideration.