Yes - I had the x series 3.0, so it would not start the upgrade. All I had to do was delete MyFlashDisk and copy the backup over. The first time I must have left something orphaned, because I had to do it again. The upgrades don't seem to care what version of OS you have.
The official F-Series firmware seems to perform slightly better on the unit than the hacked x-series did. The map scrolling is now very smooth, key beeps by default are low, etc.
In my opinion, there are some obvious usability issues that Pioneer could have addressed, but don't seem to bother others here. For example, I listen to XM radio most of the time, and I like to view the map while driving. On the map it tells me the station I'm listening to. I know what station I'm listening to - I selected it. I would like the ability for that area to show song or artist by touching it. Same for iPod or HD radio. Oh well - maybe someday someone will figure out how to hack the UI.