Did mine a few days ago, after joining the preview program and finding that the TH2 update made my S3 run like crap. I had thought about doing a clean install, this just gave me an excuse to go ahead and do it.
I didn't have a spare USB drive so made an install disc (blu ray disc actually, only used about 6Gb but I wasn't going to use the disc for anything else, and had no dual layer DVDs to use) with the media creation tool using an external blu ray player. Used a USB hub to plug in a 2Gb USB drive that had the drivers on it, and USB keyboard to TAB my way through things during setup, like skipping the product key. Booted from the disc and went through the install, deleting ALL partitions (it makes new ones for recovery and EFI when creating the new C: drive to install to).
Had a bit of a heart stopping moment when it failed around 70% when copying from the disc, but just started again and had no further troubles. It did seem to hang at a "just a moment" screen before getting to windows after the install, so I did a reboot and it was fine again, it set up an offline account and loaded into windows. I don't know about drivers but I'm thinking it may have loaded generic drivers from the install disc as it never asked me for any drivers, it just downloaded what it needed when I ran update. Linked my Microsoft account, got Office and redownloaded my apps and set things back up how I wanted. So far it seems to be going well, haven't come across any issues in the last few days. No issues with activation either. My S3 had gone through all the 8.1 updates and the 10 update prior to starting the clean install.
Overall I had a fairly good experience, not much different to my last pc install with Windows 7 many years ago. Hopefully I won't have to do it again, but if it happens I've got no reservations about having another go at it. From the look of things, if I want to start over again I should be able to just do a reset rather than go through the above all over again.