Coco as the carbon component within the soil vs. coco as your sole substrate are 2 different beasts. Ready gro that ML is using contains coco out of the bag, but in modest amounts. There's no substitute for experimentation, so follow your instincts and pay close attention to your plants.....knowledge will follow :)
I love this idea. CCH2O is always coming up with innovative stuff. This system would be really nice for me since it's pretty much impossible to run a good hydro system in vegas without some sort of major chiller running 24/7 during the summer. I'd love to try running coco outdoors in this system. I might even put peppers in it :P
Is the distance between buckets easily controlled? I'd probably want to leave only a couple inches between buckets.