Ok, have done the install and checked a few former problem areas:
Yes, playback of Universal Blu-rays with Bonus View features (i.e. Incredible Hulk) results in the "Bonus View" icon to show when screen messages are enabled. Annoying but at least there is a workaround. Is this more intended behavior?
Pan's Labyrinth HD DVD: I loaded this 4 times. I didn't notice any pops (bitstreamed) within the first 5 minutes of the movie (a place where they usually appear). However, I did have one session with dropouts galore. I'm going to attribute that to a random glitch (stream initialization failure during the HDMI handshake perhaps). If others with the title can confirm, I'll drop this one off the disc problem list.
La Haine HD DVD : This one plays and navigates without locking the player finally. Color me shocked since it's an import and fewer people own it in the NA market. I'm still unable to access scene selection, so this will likely never see a fix. Not a big deal thanks to navigation finally working!
The Kingdom HD DVD : The U-Control menus are still slow as molasses, sometimes taking 10 seconds or more to load or switch between the various fact/trivia columns. Since many HDi menus are similarly sluggish on the disc menu screens themselves, this is just a matter of poorly optimized HDi code as previously stated and I don't see it getting any better than this unfortunately.
Transformers, Disturbia and Beowulf HD DVDs in 24fps : Serious upper screen flickering in scenes with movement and yes, perhaps worse than firmware 1.3. Totally unacceptable. Things We Lost in the Fire was another I checked and I only saw a single flicker in the first 5 minutes, so likely a more intermittent issue on this title.
At least it's not all negative with 1.4...but I was expecting more (my first mistake