So I got a set, and sure enough they're just about the most perfect dice I've ever beheld. I think this is it—my one true set. Fans of mechanical keyboards often speak of the search for their "endgame," that one perfect board with just the right size, key height, click sound, physical feedback on a keypress, keycap set, and so forth. (It occurs to me that I probably haven't written a blog post about my own keyboard collection; yet another note to file away for the future.) I've found my dice endgame.
As I've mentioned before, when I run D&D, all I need are a pair of differently-colored d6s, a d8, and a d20; and maybe an extra d6 on hand for rolling characters and a d12 for the odd die check involving a 1-in-12 or 3-in-12 chance of something. This set fits the bill while having the advantage of being large and easy for everyone to read (and I do very much like everyone around the table to see what I'm rolling as I run a game). The d20 is a "0–9 twice" type, which means that I had to either ink it in two separate colors (making it kind of ugly) or ink it all in white and roll it with a control die; I've opted for the latter option, for now, as it's no big deal to roll a d20 and a d6 together and read the d6 as "+10" whenever the result is odd (as the 1, 3, and 5 faces on a pipped d6 have a dot in the middle of the die face, and the 2, 4, and 6 faces do not—making it a very easy visual shorthand, hardly any different of reading an old d20 with 0–9 twice and a "+" mark on half the faces).
I still don't see much reason to bother using that caltrop d4, though.