I think individual containers are easier to work with even if you have multiple solutions to dose. I have the Neptune DDR and having 2 containers attached makes it 3 times more difficult to clean/fill/etc. And when there is a problem with one of them, now you have a problem with all of them (like I currently do).
Those are nice and clean looking, but I agree that having separate containers is nice. Every now and then I have too much time on my hands and decide to clean out my dosing containers. It's a lot easier letting one get empty and lifting it out than it is to wait for all 3 to be empty at the same time or dumping/pumping them out.
Mind you I'm not the example of attractive dosing containers at the moment. The 170 is running on Simply Orange juice containers (1.5 L) and the big tank is running on the same for the smaller dosed items (iodine, nitrate) and pairs of 5 gallon water jugs for the main consumers (Ca, Alk).