I don't consider that mention bad.
I looked up the NOS availability of both the 7 and the 9. Seems both are still around and at a nice price.
I recall the discussions related to the ART7 and ART9. I don't recall the details. One was supposed to have better dynamics than the other. One was supposed to provide better detail that the other. One was supposed to be preferred for classical music, the other for jazz and rock.
Can anyone recall the distinctions?