Upgrade R3 4.6c to ECC 6.0, Impact on Portal.

We are planning an upgrade of R3 4.6c to ECC 6.0. i want to know what can be the impact on the Portal side with this upgrade. We are currently using EP6.0 (WAS 6.2).

Any pointers about the User Administration change, Content Management, Knowladge Management, SP Upgrade etal would be of assistance.

Regards

Nitin