I have the EEF, but I am still breaking it in. It comes fairly rough at first. But I am looking forward to using the EEF once it has smoothed out.
I was thinking about getting the WS4XX, which I assume is extra-extra-coarse. It seemed like it would fit just fine, but DMT never suggests it's suitable for the aligner. Glad to hear that it is, for there are some reprofiling jobs that really need to start with it.
Of course, one can free-hand with the smaller stones, but the whole point of an aligner system for people like me is that I don't want to free-hand and don't want to put in the time to develop the skill. While it is a plus, as you said, to be able to use the 4" stones for free hand, I suspect that most people who want to free hand will have some larger stones on hand already.
For the smaller blades, I use my SharpMaker. For my bread knive with a 10" blade that has absolutely no belly, I also use the SharpMaker. I suppose I could use the the DMT aligner system, but I would have to fix the clamp in at least two locations to cover the entire blade, and the arcing motion of the stone means that the bevel of the edge not would be even along the length of the blade.
When a knife is too small (such as pen blade) or too long (such a bread knife), the DMT aligner system doesn't work for me. But for most knives, it is my first choice.