Thanks for the follow-up StanislavZ but I agree with amitparmar.
After applying the 10.1 update, the behaviour is better but bug is still present: there is no longer the "resizing artifact/shift" when all apps are in full screen, but when moving from a desktop with a few windows to a a full screen app, this still occurs. I even managed to see the shifting/resizing appear when switching back & forth between a *Mac* full screen app (Safari) and Windows 7 full screen app (Notepad).
So it's better, but not resolved yet.