Mike, I have no halos and I sharpen as much as I ever need so this is all moot.
Your analogy is even goofier than mine.
Sorry, I just don't buy it, but I'm glad it's helpful for you.
There's plenty of validity to "use whatever works" so I understand and I won't dispute what works for you. I'll just make these final thoughts for you to consider.
The fact remains that DFS can simply be pushed a lot harder without artifacts. Some may need that ability. Others (like you) maybe not. But if you don't, it's probably only because you've learned to work within the limitations
of USM. I'm sure, like the rest of us, there are times where you would like to use a larger radius but you don't because you know you can't without causing USM halos. The larger radius is very useful for that occasional soft photo, landscape where you want high contrast, image where you want to remove fog with a large radius sharpening, or a very large print where you need larger radii based on image resolution versus print size (something that, as John pointed out, Qimage does automatically or, as you may prefer, be adjusted manually).
But again, to my analogy of the speakers. We're looking at a technology in DFS that allows you to push harder, just like a real audio speaker can be pushed harder than a phone earpiece. If all you've ever heard is a phone speaker, you may not think you need anything better and you'll work within those limitations which is why I suggested just trying it rather than guessing what it can do. I know
what it can do. You can put any radius/strength that you like into USM, even smaller ones, and as soon as you switch to DFS, the sharpening remains nearly identical except when you click DFS, the halos disappear. When presented with two algorithms, one with an obvious flaw (USM = halos) and another without (DFS = halos completely gone), I'm not sure why anyone would want to use the inferior one. And once you see the difference and you can switch back and forth between USM and DFS, you begin to see that even radius values in the .5 to 1.0 range have artifacts (not necessarily all halos as pointed out below) because when you switch to DFS, you can see the same level of sharpening without the brightening around edges and even inside "holes". Even radius .5 to 1.0 can cause specular highlights in small areas where, for example, light shining through tiny holes in/between leaves can turn what should be a blue point of light (blue sky behind the leaves) into white. After working with hundreds of images under both methods, you begin to spot a lot of deficiencies like this (even though some may be small) in the USM algorithm.