I remember playing the Rithmic at the LBGS a few years ago. It was a classy instrument, gorgeous to play.
The tone was a bit too refined for my tastes, and the nut was extremely narrow.
I've always thought that the studio version of Spirit of Radio has a distinctly uncharacteristic Geddy tone, very clean and tight. Of course, the playing and notes give him away anyway.
A Gibson SG bass? They were only introduced a few years ago...
Forgive the pedantry, I'm sure you meant one of the EB variants but this thread does seem to be intent on some sort of accuracy about... something.