I have recently completed our upgrade to the latest version of SDP (Version : 7.0.0 Build Number : 7010). We've been using AD Integration all along since v6 build 6008.
After the upgrade, and after enabling passthrough authentication, suddenly no one can logon with their domain credentials. I tried disabling AD PTA, and even restarting the SDP service - still no joy. The only way I can get in is to be on the server running SDP and logon using the local tech credentials.