"In terms of differences among the models: the TS808, the TS9, and the TS9 reissue are in fact built on the same circuit board pattern. For these three, THE ONLY DIFFERENCES ARE THE OPAMP TYPE AND THE TWO OUTPUT RESISTORS."
Per the Technology of the Tube Screamer which is otherwise probably way more info than anybody really needs.
Well, I meant in terms of tone.
And then where does a TS7 fall into this mix?