There are several professional level hand tools that do as good a job as the expensive powered machine tools. But it would be hard to do a good job without looking at the blade as you sharpen it. (The same applies to the powered machine tools, plus they don't fit in your skate bag.) So unless you are very flexible, you have to remove the boots from your feet, which takes time. Plus, with most hand tools or machine tools, it takes a time to learn to do a good job.
The tool you found is very widely sold in pro shops. I know hockey and figure skaters who love it for emergency repairs. Those tongs make the tool self-centering, so skaters can apply it themselves in a few seconds without removing the skates from their feet. It takes very little time to learn to use. It quickly removes nicks as well as edges that have been smashed flat.
The trade-off is that it makes the blade thinner at the bottom, and removes the sharpest part of the edge. So the blade skids on deep edges. A very important advantage of this tool to a pro shop is that the results do not compete with the shop's professional grade work, yet it works well enough to make the skater stop looking for alternatives.
Did any of you attend the seminar for elite track coaches at a recent Dallas PSA conference, in which a sharpener of my acquaintance showed coaches how to do emergency repairs using nothing more than a small round stone? He showed me his technique. With no centering guide, you have to be pretty careful, and it is very hard to get as sharp an edge as I personally like.