Kodak employees, or Kodak affiliated researchers, concluding that Kodak products are as good as the ones from the competition ... did you really expect something else?
Nevertheless, do you happen to know when they conducted their research? The 1947 recipe of Edwal 10 looks a lot like D-23 albeit with less metol than the version that is listed on this site and various other forums.
Mid-1940s - and they're pretty explicit that the aim was to match a PPD-sulfite developer while reducing the problem side effects (toxicity - they keep emphasising how dangerous PPD is - in 1945!, speed loss, lack of sharpness). They got there initially via DK-20 (which caused dichroic stain on some emulsions), then D-25 - and adding more and more bisulfite to slow it down further to allow the sulphite more time to act on the grain. With modern anti-dichroic stain agents now incorporated in emulsions, KSCN containing developers are starting to reappear (see Adox, Spur) possibly because there is some evidence that their solvency may allow better access to the iodide in the emulsions.
It is possible to make a CD-4 developer (because no one should be messing around with unsubstituted PPD in a home lab) that actually performs well in terms of speed and sharpness, but it requires a lot more to it than adding an extra developing agent (which may be doing most of the work) and hoping.
The reality is that Kodak etc wouldn't spend the time & effort to research and take a product to market unless some pretty ruthless tests showed it was provably better - this is where Kodak and others pulled ahead of the amateurish developer-tasters, who didn't have electron microscopes and microdensitometers, let alone emulsion research divisions to investigate the grain/ speed/ sharpness relationship. That Ilford, with a significant basic science research group at the time, ended up essentially making the same product as Microdol/ Microdol-X in the form of Perceptol, says far more about how accurate Kodak's pinpointing of the useful mechanism was. It's terribly easy to want to make folk heros out of some kind of supposedly heroic amateur chemists slowly poisoning themselves with PPD in their garden sheds rather than teams of white-coated researchers in large corporate entities coming up with elegantly simple and much less toxic solutions - especially because it doesn't fit easily with some of the popular (and often fairly well founded) narratives about mid-20th century corporate behaviour with regards to chemicals and their effects on the end user and the environment. Ironically, the use of PPD in hair dye (and other dyes) until very recently is actually a pretty clear illustration of that behaviour.
The other problem with people playing around with many developers today is that the 'tests' they do seem to lack even the most basic sensitometric controls & comparisons - and often rely on consumer grade scanners with questionable MTF and noise characteristics, which they then proceed to sharpen the life out of.
