A quick post to say the upgrade process from Windows 8.1 on Surface Pro 3 (core i7 / 8 G RAM) went very smoothly and was very quick.
After about 15 min, Windows has been upgraded to Windows 10 with no issue. Everything from the application (both Windows App or Desktop App), content (cached from OneDrive and OneDrive for Business) is still there and correctly configured.
Good news too, you don’t have to suspend the Bitlocker Protection, the install process does it for you, meaning you don’t have to stay around while the upgrade is in progress (as there are few restarts 
).
