I read that review and was surprised to see him bashing the speaker driver. I don't believe he understands the design of the unique transducers in the K1000, which are unlike anything before or after them in headphones. He should read the original literature and manufacturer's comments from the Stereophile review, where the engineer explains their design. Among other unique features, the rear of the K1000 has more open area and less impeded than any other magnet structure by using a ring magnet structure. It also doesn't create a confined air volume like other headphones with earpads.
IMHO, you can safely disregard most of what he said about the driver. His position was that they were no good because they were old with no supporting evidence (except his subjective assessment of the headphones). He indicated that newer drivers were "better" without specifing which particular drivers he was talking about (they can't ALL be better) or what about those better drivers makes them better. He made no measurements of the AKG driver or newer drivers to prove his point, he didn't address the K1000 design in particular to tell us what was wrong. Basically, his position is that newer driver designs are better because they are newer, which is pretty much a content-free statement.
His subjective assessment is what it is, and that's fine. But he tried to buttress his assessment with the strawman that "it's an old driver, so what do you expect" (to paraphrase) and that was not proven in any substantive way. Who knows, maybe it's impossible with today's technology to make a better driver in the context of the K-1000 design. I don't know and neither does he!