I like both systems but I think I like Silvieras system better. The one disadvantage I can see, aside from roofing, is that it makes it difficult to have permanent beds for perenials. I am not sure what your climate is like but I have rhubarb, asparagus and strawberries, as well as quite a few herbs, which are better in an established bed and take a few years to get a good crop. I'd have to have them outside this system. I also have whole bunch of plants that self seed which saves me on buying seeds and also saves labour. I just pull out the excess and feed them to the chooks. My climate also means I have winter crops so I'd need more sections to rotate to accomodate them. As for the moat, collecting manure looks like it would be pretty labour intensive, and they would pick their run clean pretty quickly but i guess it would be pretty easy just to throw any greens, weeds, thinned plants etc, over their fence from the vegie garden in to the chooks.