Full Tang Clan, I have a Gatco and I have a friend who has the Lansky. They seem to be very similar. They do leave marks on the blade, but with a piece of paper towel between the clamp and the blade it seems to stop this from happening. Be sure not to over tighten the clamp.
I find both only good for reprofiling the edge on well used knives or bad factory QC, I then take it to the Sharpmaker to put that hair popping edge on them. Personally if I had known the difference at the time I would have purchased an Edge Pro. Although more expensive, I think I would have been better off in the long run.