After having rooted before, I had already installed OTA Rootkeeper and backed up everything. I didn't receive a spontaneous request to upgrade .21 to .22, but when I checked today, the firmware update was available.I temp-unrooted witk RK.
While downloading it (on the go, on the train to work), it hung on 99%. I decided to reboot and try again. Now the pop-up did actually come, said there was an upgrade available, and that the file had been downloaded. I clicked "OK" when asked to ugrade, and it started to verify the file. No error came up, and it started to install. However, I was confronted with an Andy having open-heart surgery
-- no-go. Luckily, after hard reboot, my dear TF700 (I love it, with all its faults and quirks
) booted up again and restored the previous configuration (thanks, ASUS).
I do not know if the mobile download has screwed up, or that somehow something (whether an installed app or so) screwed this up. I just wanted to let you know that even when it does screw up, you're probably going to be thrown back to the previous state and wouldn't lose anything.
Might save you from the first stages of either cardiac arrhythmias and/or clinical depression.