I have tested out Wzors RTM .iso since it was released, and with that .iso file, I can upgrade a valid computer, then wipe the disk with another .iso file, then start up from the Win10 .iso file, and install a clean install of Win10, and still get activated. (like MS said it would be) But with the .iso file I made from the .esd file in $Windows.~BT, a clean install on a previous activated computer, will not activate. Thats strange. Has to see how this will be with the .iso files when it comes out on MSDN, but not a good start. Edit: It can be some activation limit I have hit. The VM was first updated to Win10 (1. activation) then a clean install (2. activation) then moved to another server (3. activation, then a new clean install on the new VM (4. activation) all in one day. Now I can't activate with a clean install if I use the Wzor .iso either.