Aah - good to know!
This whole debate about whether to 1:1 backup a Blu-ray (usually to a BD-R DL) or shrink it kind of reminds me of my own personal history of backing up DVDs.
From 2002 to December 2006, DVD+R DL were expensive. I put a few favorite movies, discs with 2 versions, discs with DTS tracks, or discs requiring compression of less than 50% on DVD+R DL, but for the most part I shrunk them to put on DVDR (single layer). Since I owned a CRT TV I could barely tell the difference.
When January 2007 rolled around, I knew I'd be getting a 1080p LCD soon, but couldn't afford it just yet. Verbatim DVD+R DL were around $1.50/disc, which kind of sucked but was at least bearable. A 1:1 backup vs. a compressed backup was bound to make a bigger difference on a 1080p widescreen LCD than a 480i 4:3 tube TV. So I started doing 1:1 backups of all new movies.
In November 2007, I got my 1080p LCD, and continued doing 1:1 backups. About 6 months ago, I went back and made 1:1 copies of all the old ones. So, as of just recently, every backup I have is a 1:1 copy of the original.
Right now, BD-R DL are expensive, AKA $8 a pop. And the movie may appear the same on a BD-25 or even a BD-9 on say, a 50-inch plasma. But one day, you may get a 1080p projector with a 100-inch screen, or even a 4k projector. When that happens, BD-50 vs. BD-25 vs. BD-9 is bound to make a bigger difference. At that point, you have to decide whether to just stick with your lower-bitrate backup or go through the arduous task or re-backing them up to BD-50.
So far, I've made backups of several BD-ROM SL movies to BD-R SL. And I've made backups of a few BD-ROM DL movies to BD-R DL, aka Avatar. But for the other Blu-ray movies, I have just the original with no backup. So far, I've refused to make a shrunk backup copy of a Blu-ray movie, just because I don't want to have to one day decide whether I want to "retro-fit" my collection again.