Have been running on 8.1 for about a month now, so far so good. No problems just took a lot of time making sure everything was updated, including hardware drivers.
Did a Recovery Disk install to make sure I was staring with a "clean" copy of Windows 8. Ran all those updates then moved on to upgrading to 8.1 followed by more updates and patches.
Due to a client request I also tried an install of DataCAD v11 and found the Win7 hardlock workaround didn't get things working. As a last ditch effort I found the new owners of the "Aladdin" hardlock, SafeNet Inc. had an updated driver for 8.1. This combined with the Win7 workaround did the trick, panicky client aside I much prefer working in the newest version of DataCAD.
Now if the 3Dconnexion Space Mouse would support a driver for DataCAD ...