I've checked the records, and the movies we held the longest were The Deer Hunter (six weeks), Under the Sand (six weeks), The Limey (seven weeks), Mulholland Drive (eight weeks), The Blair Witch Project (11 weeks), and, leading the pack at 13 weeks, The House of Mirth.
Of these, only Deer Hunter and Under the Sand are downers. The others are ones that we couldn't find the time to watch or couldn't get into the right frame of mind for several weeks. After we had Blair Witch for for two months, it just made sense to wait and watch it around Halloween. And I had no interest in the House of Mirth, so Liz had to wait until she had some time when I was busy elsewhere so she could watch it. I'd say as far as we're concerned, the results are inconclusive. Looking over the list, we haven't rented many depressing movies, and our average hold time is one month regardless of the picture. We've been meaning to watch more movies through Netflix, so hopefully our churn rate will improve.