PJ,
That is an interesting observation about break in! I did notice some problems with sync/lock when I got my DI/O upgraded to Mensa Plus (a whole lot of parts were changed). When the newly upgraded DI/O was paired with my Cary, there would be the occasional loss of lock. It would lose sync more often on a Pioneer 47Ai (universal player), though this was improved when I turned the video circuitry off. I don't have the 47Ai as it was a friend's (I only had it for about 2 weeks). But, I now never lose lock on my Cary, and the DI/O is now also totally broken in.
I should try my well broken in DI/O with my DVD player.