If there is a concave area length wise down the middle of the ski shown - 116 mm waist, the inboard leg of the SVST unit would be riding in probably the low point of the concavity. Tipping up the out board side of the guide.
The Artech unit on the other hand would be riding higher on the up slope of the other side of the concavity. Probably less side to side tipping would be experienced.
If the ski is much narrower, The SVST unit would probably be riding on the opposite up slope similar to the Artech unit in its current position.
One reason I went for the Final Cut is that the Artech/Toko design looked too much like my old Swix guide, which wasn't wide enough for an Arkansas stone and probably wouldn't fit wider tools like the SVST diamond files, and which I didn't much like the feel of (it's now out of production). However, your file guide might be wider...
Aside from the length, would a concavity cause the Artech/Toko design to wobble because one corner would run further up the far edge of the base than the other? The SVST's feet run at the same distance from the edge, which means that it's stable no matter what the shape of the base is.
I'm not saying the Artech/Toko design is bad or anything, just wondering if I'm imagining a problem where there isn't.