A couple of observations on 10F4 so far.
Using Mark & Delete in MyPlaylist is MUCH faster. I cleaned out many recordings today and expected it to take the normal 5 minutes or so and it was done when I looked up. Maybe a minute.
Moving SLs around in the Prioritizer is also MUCH faster than F1 was. 1-2 seconds now versus 5 seconds on F1.
However, I have run across a bug that you only run into when you press the wrong remote button. I was changing the Episode Type in an SL. When the list was expanded I pressed the Right Arrow key (which shouldn't be allowed) and the values on the SL screen disappeared and I couldn't do anything other than use the BACK or EXIT button. Checking some more it appears the pressing the Right Arrow in any of those fields in the SL edit screen causes the same problem. Once I made that mistake I could no longer edit SLs. I needed to RESET the unit. So don't try this unless you're prepared to RESET your unit.