I have that tool, and have used it only once. It worked, but I didn't find it necessary. With proper lube, the carbon (granted, use NiB and Nitride) seems to wipe off easily.
That being said, I think the tool is a great idea, but has it's short comings. For starters, it should be made in 3 pieces (it is currently 2. A handle, and a fixed, flipping, blade/tool). If they made it as a 3 piece (handle, and TWO separate "blades"/tools) it would be more compact and be able to fold into itself (currently it does not. There is always ONE portion of the tool exposed, as it is a "switch" type blade/tool). This failure (design) makes it less easy to transport, store (such as in a grip), etc.
I would love to see this tool with TWO separate scrapers (handle, and two separate "tools/blades" that fold into that handle). There is NO reason to have only one blade/tool (which causes ALWAYS one protrude).
Great idea, poor execution.