dunno anything about the gsg model, but we are using the first one and it works great, but ONLY if you set it up with sediment tanks before it. On its own it clogs up too fast.
We have two 55 gallon drums (with baffles) that the water goes through first so most of the sludge stays in the drums. By the time it gets to the filtration unit its pretty clean.
if you look around you'll find the video Ryonet shot in our shop with Matt (our production manager who built it) explaining how it works.
pierre