Hi,
if your main goal is to reduce logon time you could also use a shared mandatory dummy user for all users:
Using ZCM Bundles to speed the login for students at shared computers | Novell User Communities
The logon time is about 5 seconds - 10 seconds to ready opended internet explorer.
I use this for some stand-up computers since 1 year now. At first sight it seems wierd to share a dummy user amongst all users. But we have shared computers anyway.
In one year there has been no issue with this solution. However its fundamental to configure the machine correctly since we cannot rely on the SID as security boundary.
Logon with a Windows Dummy User could also be achieved with pgina (pGina)
best regards
Markus