Just took a look at Sterling's website. At first glance, these types of sharpeners really appealed to me. So I bought one, from Meyerco, which works on the same principle. Basically what happens is when you pull the blade through, the two sharpening surfaces (in Meyerco's product this is a pair of steel disks and a pair of ceramic ones) actually "peel" or strip off steel. The result is less than a good edge. What I tended to get was a wire edge - totally worthless.
One tendency is for the blade to temporarily "grab" at any noticeable imperfection (knicks & chips) in the blade, then continue on down the blade. When this happens, the design of the sharpener generally causes the imperfection to get worse. My tendency was to over compensate with more pressure, which also makes it worse. Even when I managed to not add additional pressure, the imperfection was already worsened. Once this happens, these styles of sharpeners are basically useless. I then went and bought a Razor Edge kit to fix the damage. What I learned is that only a good hone can remove imperfections easily without removing too much steel.
Think about what the opposing sharpening surfaces are doing to the blade. They impart a kind of an s-curve shaped twisting effect which is magnified as you increase pressure. It's been a long time since I had mechanics of materials courses in school (I'm a computer analyst now), but I just can't see any way that such pressure can be anything but bad for an edge.
Although it seems like a great idea, I've found it to be a waste of money. I'd like to sell mine, but my conscious won't let me do that to someone else.
I don't think this is indicative of Meyerco's general level of quality. I have a couple of Meyerco's Blackie Collins designed knives and I like them quite a bit (not the same class as BM though), but I'd give the sharpener a 2 on a 1 to 10 scale.
If you can try before you buy, do it. Otherwise, you'll probably be better off getting something else. I don't remember the company, maybe Lanksy, but they make a mini sharpener that is small enough to fit a keychain. It uses two very small round ceramic rods inside a plastic frame which is about 1"x1"x0.25". I keep this on me when I'm canoeing. It's only good for touching up an edge (blade has to be about 1/4" or less in thickness), and only last a few times before the ceramic is clogged (very difficult to clean), but at less than $5, it serves the same purpose as the Meyero sharpener, costs less, and doesn't magnify imperfections.
One note - I actually bought the Meyerco from Blackie at a manufacturer's rep day at a large local knife shop. He stressed the importance of very light strokes. Although I tried, it took forever to get a decent edge this way. Certainly, the more pressure you use, the more steel is peeled away. If you can learn the right amount of pressure, and have patience, these sharpeners might work.
For me, their tendency to worsen imperfections, inability to make or maintain a double edge, unsuitableness for single bevel edges, and intrinsic slowness make them expensive (at any cost) dust collectors and drawer fillers.
On the other hand, they might be perfect for maintaining serrated edges. I haven't tried that.
My 2 cents worth. For 4 cents, I'll make the same pitch, but wearing something nicer than a t-shirt.
P.S. I can thing of one instance when these types of sharpeners could be handy for me - when I have a knife with an edge that has no knicks or chips and I want to remove a lot of steel fast. In my case, though, the Razor Edge Systems is going to do the job.
[This message has been edited by Codeman (edited 26 May 1999).]