I have personally never done any comparison of the two formats. At the time, each was clearly an improvement over that which preceded it. They have relatively comparable specs with regard to frequency response and dynamic range. They also have individual issues with regard to artifacts. In this area I think the Laser would probably fare better. In addition, tape has the disadvantage of physical wear, degrading the playback over time (which could also exacerbate the severity of the artifacts).

Also, for the history record, RotJ was not released theatrically with digital sound. It did mark the showcase debut of the first commercial THX Theater System presentations, but the release format was standard Dolby format 42 (6-track mag - Baby Boom – Dolby A). The first feature film officially on record to be released with digital sound was Dick Tracy (Cinema Digital Sound – 1990). Although this was pre dated by a single digital sound presentation of “HOME OF THE BRAVE” at the 57th Street Playhouse, New York City in 1986. (The system utilized SMPTE timecode on 35mm composite magnetic film controlling VHS tape. Playback via 4-channel quad-amped system.)