I find that "study" rather funny as they are treating two totally different mediums the exact same which just happens to suit the peat moss... It is almost like they have some sort of vested interest in the results. I would have to wonder if this study was funded by the peat moss industry in some way.
I myself have grown with both and in my situation Coco is the only thing that will let me do what I do. I could not do it with peat, because it holds way to much water. Peat is more like traditional soil, as most soil growers are probably using peat and not top soil. But Coco is a whole different animal, you can not let coco dry out because it is more like hydroponics, so just like you wouldn't turn off your pump on your drip system, you do not let coco dry out, you basically have to feed it every day. You have to deal with the C.E, by either amendeding it with organic sources of N, Ca, and Mg or adding a coco based nute when you are reconsituting the dry bricks. Cation exchange is a good thing when it comes to coco if you understand it and use it to your advantage.
Basically in coco coir the medium itself will hold everything that the plant needs within the medium itself and pass the elements to the plant as it needs each one. Yes coco itself is high in K, but once again if handled correctly initially then it is IMO, the easiest medium to go totally organic with because once you deal with the C.E then you are basically replace the elements in the medium and not in the plants. I know, it is somewhat hard to wrap your mind around at first, but if you do research on true organics, that is basically the premise, you are feeding the medium, which in turn feeds the plants. But using coco you have the added benefit of all of these organic elements being chelated and held for the plants and beneficals to eat what they want, when they want. It is truely wonderful.
I will make a bold statement and say that with everything I have done, organics, and I mean true organics is by far the best. The method I am using now has me producing the largest and most healthy plants I have ever produced. Most plants are healthy until chopping day. I am no expert and I am really still learning myself with only starting into organic a year and a half ago, but I am starting to understand and realize some of the potential. So I am a fan of coco of course but I am a bigger fan of organics, and right now coco is all that is available that will allow me to do what I do.