I had various issues with my 950XL that I had restored from a previous backup-- iris scanner would stop working, very occasional random reboots, etc. The showstopper was when the update was pushed out last week. I ended up in a death loop where it would attempt to download the update, give me an error that I had insufficient storage space (even though I had a good 23 GB free), and then reattempt to download the update. It was a MASSIVE battery drain as it continually tried to download the update; as a bonus, there's no way to force it not to update. So, I pretty much had to hard reset. I was fairly confident that the issue was restoring an old backup and that a fresh install would fix a lot of issues. I was right.
The update downloaded right away, haven't had any issues with the iris scanner or reboots, everything works like a peach. It was a huge PITA to set everything up again the way I wanted but, ultimately, one day of pain for (hopefully) several months of stability will be a good tradeoff. We'll see. For the moment I'm glad I did it.
EDIT: In some ways it's similar to upgrading a desktop Windows installation vs. a clean install. I've never in the long run regretted doing a clean install.