I've recently pulled my individual seasons of the series to compare to the quality of the complete series. I'm particularly interested in seeing how individually released seasons 4 and 5 look compared to the versions on the complete series. The individual releases were 4 discs each while the complete series versions are 3 discs so I'm wondering if there was any compression due to the disc reduction. I'll check that out over the next few days and see if there's any difference

Looking forward to your findings.