[TYPO3] session vars - ses and user

[PEF]

Hi,

I want to change my session vars from 'ses' to 'user'. Something tells me, that I can't use 
"$GLOBALS["TSFE"]->fe_user->sesData" with session vars of type 'user'.

Do I have to use getKey instead of sesData?

The reason I ask is that data don't behave as expected, when changing the session type to 'user'.

Regards
Peter Falk