@Jakeco it took a little for windows8
windows 8 release Okt. 26, 2012
Stardock then delivered the Windowblinds beta on June 06, 2013.
I could imagine that Start10 has priority atm, not sure though but it would make sense.
I found a topic about this:
As to your question about upgrading and uninstalling...
Make a backup of your Boot-drive best would be if you could make a clone.
Unload any applied Windowblinds skin / unload windowblinds - restart the system and then upgrade.