I had a Lansky for a while. I wish I had bought the GATCO system. The Lansky is easier to find specialty hones for (Arkansas, black Arkansas, ultra fines, ultra coarse, etc.), but the Gatco has wider hones that will work much easier and faster, unless you plan to do recurves. I don't know how correct the Gatco angle holes are, but the Lansky holes are usually 4-degrees off (when the edge is a half an inch from the end of the clamp, which is usually where I clamped it). If my memory serves me correctly, the 20-degree hole on the Lansky is about 15 or 16, the 25-degree hole is closer to 20, and the 30 is about 25 or 26 in reality.
I think both clamps are made of metal (aluminum probably), and yes, they scratch the finish on blades. Put a layer of duct, or blue painter's masking tape on the blade or inside the clamp jaws to prevent the scratching. If you want to sharpen a tanto, the Gatco will give you a cleaner and more distinct corner between the tanto tip portion and the regular edge. Just make sure you sharpen the two portions seperately so you don't round the stones. The Gatco works better than the Lansky for tanto's because it has the wider hones.
Clamp stands and grips are optional with either system. Both systems have clamp jaws that will open up fairly wide.
Bugs: Sounds like you need an Edge Pro.
If you need to do stock removal to reshape the bevel on a severely dulled knife, the 204 will not work so great. I tried using a demo 204 in a store, and I simply can't see how you can do any serious sharpening on it without wasting a lot of time.
