That's not something I'd agree with, the 009S is a definite upgrade over the older 009 but it does further expose the inherent limitations of the design. The bass in the 009 sucks, there is no doubt about that so while Stax fixed the off tonality, they didn't fix the bass issues. I have a feeling that it is due to the basic driver design so they'd have to do something drastic to fix it but further experimentation is needed.
What I find really fascinating are the discussions with pro users of Stax and what sets they are using. About 1/3 of my amps go to studios and other professional environments, professional musicians and the like and none of them use the 009's, either version. It's always the same line, they don't sound real or some variation of that. Same goes for the new Lx00 series, those not using 007's or 4070's have a stockpile of 207's.