I agree, they are quite different, but that's the closest knife I personally own from CPK. The GSO-6 is a world apart from my SDFK and DEK1, but it's closer in edge thickness to the DEK1.
As far as I can tell, the most comparable thing CPK makes to the GSO-6 is the Basic Field Knife, and per Nate's specs it's .030" at 20 dps, the same stock thickness, and seems to have a similar primary grind angle based on the bevel height. I don't think either knife would qualify as being thickly ground for its intended use, but I digress.