Thanks for the link, I am pretty confident that my current configuration with kerberos auth works fine with 4.0a too.
Due to our Infrastructure I need to change the authorisation of our system though, letting Apache deal with the details of who gets in and so far I didnt manage to get Share to work with external auth on 3.4d.
I just wonder if I can move on to 4.0a or if I should continue to work on 3.4d, making it work there.