Hmm.... Ok, I'll be the one to rock the boat. :P
I'm all for gadgets, but I see a few issues with this one. If you have multiple places you'll use it, then you're going to be moving it all over the place with the good chance of misplacing it. There's also very little chance that two vices you own will be just the right size to use the same device. And in a non-hobby shop environment with multiple people using it, it won't last a week.
The device pictures is essentially the same as using parallels with a certain type of parallel "keeper". While I do like the idea of keeping my "good" parallels away from some quick "punch a hole through this" job, I also don't tend to drill through parallels (or vices, for that matter).
I keep a few pieces of pre-cut and deburred flatbar to use in these sketchy cases. They're soft so if you accidentally drill into them, it isn't a big deal. They're also cheap, and easily replaceable - or even consumable for some jobs that *do* require drilling very close to the edge.
How do I keep the flatbar where it's supposed to be? Metal strapping/banding. You can find it just about anywhere if you're looking. If not at your own work, check behind someone else's and you're sure to find a skid with some of this still half wrapped around it. It bends into shape while still retaining some spring. It doesn't take a large assortment of "V" or "W" shapes to cover the opening range of most vices.
On a side note, banding/strapping also comes in different widths and thicknesses. Collect different sizes and you can make yourself some reasonably accurate SUPER thin parallels for drilling and milling close to the vice jaw.
The other way to tackle this is to make step jaws for your vice(s). I devised a set the last place I worked that had two different steps, each at a different height, and one of them had a work stop. They were useful for the majority of jobs I did there, requiring me to swap the jaws or use parallels for only a few oddball setups.
Don't get me wrong, I think this would be a great little project for a beginner to develop their machining skills. But for someone already possessing a bag of tricks to pull from, I'd suggest they pass on it.