Is this setup secure? OpenVPN via RADIUS on AD2008R2

[Vorkbaard]

Hi, I followed this and this tutorial to have OpenVPN authenticate against Active Directory 2008 R2 through RADIUS. Contrary to what it says in the second howto, I did not check 'Store password using reversible encryption' in AD.

I can't get OpenVPN to work if I set Server Mode to 'Remote Access ( SSL/TLS + User Auth )' in the OpenVPN Server config in PfSense 2.0.1, but it does work if I choose 'Remote Access ( User Auth )'. I assume that is because the certificates would have to be stored in AD as well, and there are none.

Under Cryptographic Settings I did check 'Enable authentication of TLS packets'.

Is this setup secure, in the sense that someone using Wireshark for example would not be able to sniff out the credentials on either side of the tunnel? Or should I really need to use SSL/TLT + User Auth?