Re: My gf is going to love this!
"Am I right to assume that in a regular situation this would result in my gf getting stuck whenever she tries to log on? I'd say that's one more compelling reason to stick with Windows 7 for now."
No, that's incorrect. The boot-time encryption key is stored in the TPM of the computer, and is (pending hardware verification) automatically used upon starting the computer.
The key that's stored on Microsoft's servers is the RECOVERY key, used for force-resetting the encryption key in the instance that the TPM's encryption key is cleared for some reason(such as the hardware in the PC changing in some defined manner, causing hardware verification to fail).
It's also used when attempting to use Windows' boot-time startup diagnostics on an encrypted drive.
It should not change the NORMAL operation of the computer, nor would it affect the ability of local user accounts to sign in.