I had one lockup so far. I was trying to duplicate Mike's issue with losing the center channel, I didn't have a problem going between the same video with DTS on a network and a USB, then I re-read the post and saw it was going between DD and DTS, so I played some video with DD from the network and stopped it, and it locked up on me at that point.
I got it to shut off by holding the on/off button on the unit for 5 seconds or so. I don't know if that's documented, I just tried it from computer habit.
I don't really plan on using the video playback for this unit, I'll stick to my HTPC for that. I did try out the internet radio app and that worked well, so I'm happy with that.
(ah, I see the 5 second thing is mentioned in the troubleshooting section of the manual)
There really isn't any mention about the Speaker Level button in the manual, other than there's a button marked "speaker level" on the remote. Luckily the settings you make aren't per input, so you can adjust them when watching a video from the unit and it sticks when watching something from a HDMI input. Luckily I found a trick accidentally while watching my DVR through HDMI 1, if I held down the Speaker level button, it would display info on the LCD and I could scroll through them, so I was able to make an adjustment.
Now I gotta get my Harmony One setup. I noticed the problems with the 535 settings too, guess if Logitech hasn't updated them yet, I'll just have to have it learn some commands from the remote.