The value of ISO playback for me is music Blu-rays (a growing part of my collection), DVD-As (not growing as fast but large none-the-less), and concert DVDs.
Movies were never the primary reason for ISO playback for me, but I use it for the few movies on Blu-ray or DVD that I own that I rewatch frequently.
Sorry, off-topic. Back to 103 Technical discussion.
Well the 103 (prior to the current beta) plays back all of my music/concert Blu-rays loaded as BDMV folders which is just as good as ISO playback as far as I am concerned. I would never have the space to load all 250 of these discs that I own so I only have the ones I play most often loaded on the hard drive. I didn't bother loading any of my 300 plus BR movies to the hard drives as their playback frequency is much less than for music and concerts.