Any issues with that?
Nope, shouldn't be any problems - MSDN gives you access to a full edition image.
That being said, remember the MSDN licence terms that it should only be used for development and/or testing.
I can report that I successfully took advantage of the Windows Anytime upgrade (Vista Home to Vista Ultimate.)
It preserved the old settings. All that I needed was the Product Key.
My point: technically upgrading from one Windows edition to another is easy. As it happens, I used an MSDN product key for my test machine upgrade. No problems.
All the hassles come from decyphering Microsoft's licencing rules.
I've successfully upgraded win 7 starter (OEM) to Ultimate using an MSDN key which was generated in August 09...
initially I just wanted to upgrade my notebook from starter to pro (I don't need bit locker and other ultimate features)... so i've generated a pro retail key on MSDN today... upgrade failed... kept telling me the key was invalid..
not sure if it's to do with the pro vs ultimate or when the key was generated...