Zombie, out of curiosity do you know if ILM saved the final digital renders for the re-comps and cgi shots back in '97?
My guess has always been that they didn't, since the '97 cgi shots in the 2004 transfer exhibit filmic anomalies like gate weave. Just look at the beginning of the new entrance to mos eisley. The "camera" is supposed to be stationary at the beginning of the shot (where the asp droid swats the hovering droid that's annoying him), but the frame isn't remaining perfectly still. In other words, it looks like it was scanned off the o-neg like everything else.
The whole reason I ask is that it seems stupid to do a 3D conversion of the OT-SE using a scan of a filmout of a cgi shot instead of just going back to the original cgi shot.