I have tested the privileged extension recently and figured it may be useful to share my experience here. I first tried version "200", but that failed for some reason - I don't exactly remember why, but I ended up just removing it.
Now I have been able to install the "203" version along with the stable 0.102 client package. I sideloaded the .zip file I found on the website, after checking the GPG signature. (Note: I couldn't find a trust path between my key and the signing key, or the keys signing the signing key, even though my key is in the strong set, so that's something that may be improved...)
I did the sideload in TWRP, which worked fine, and restarted after flushing the Dalvik cache (although I'm not sure that's absolutely required. (It would be nice to have step-by-step instructions on how to do that flashing for regular users, but I guess this is stuff people like me can do. )
After the reboot, I decided to test upgrades and install. I had a rather confusing experience. I tapped the "refresh" button to fetch new sources, and F-Droid found some updates, which it promptly started downloading. After the download was completed, the progress bar was just full and nothing seemed to be happening. Until the download progress just disappeared without any further information.
Some packages disappeared from the list of updates - I guess they were uploaded?
I think it would be very useful if there would be a notification, when a package is installed in the background, that the install was completed. Something like "Package foo upgraded from 1.0 to 1.1 sucessfully" or something would go a long way in getting feedback... In particular, one of the apps that was being upgraded was f-droid itself, and that was even more confusing, because at some point f-droid shutdown and I ended up in the home screen. Tapping the f-droid app gave me an error like "No such app found". The only way to return to F-Droid was to go back in the task list and tap the F-Droid window, which then resumed with the new version (presumably). (This is not a new problem with the privileged extension, mind you - i was having this all the time when f-droid would update itself.)
I haven't tested the new alpha version - I will do so soon - but considering that last usability issue, I'm always scared that f-droid upgrading itself will break, even though it always manages to recover somehow...
Thanks for that extension, it's a great improvement that makes F-Droid a real rival to the proprietary app managers. keep up the good work!