I've the two dog version, Educator 400. It works fine, light is helpful when it gets dark.
Only limitation I found with the 2 dog e-collar is I can only leave one of the dials on one dog not fixed rather than both dogs' not fixed, in case i want to adjust them at will. So if dog A is not fixed, dog B will have to be fixed if I don't want to affect the level of dog B's, vice versa. For example, if i want dog A set at 5 (and not fixed at that level so I can adjust without having to "unfix" it) and dog B set at 10 then dog B can't be unfixed without it being affected by the adjustments I'm making to dog A's. This is not much of an issue for me since only one of the dogs needs to be unfixed. With two individual remotes, the going back and forth I don't think is faster/easier than just unfixing it with one remote.
Not sure if this is the same "issue" with other brands/versions.
I've accidentally pressed the wrong buttons before. My dogs just looked at me like "did you want me to stay close?" I apologized and they got over it in a second since it's just a working level ping. With two remotes, I think I'll probably confuse the two in moments of distractions as well.
I've the one dog as well and prefers the two dogs when I'm out with both.