REQUIRED_INTERFACE still valid on 7.5?

I haven't had to use REQUIRED_INTERFACE since version 6 days, but I was recently asked if there was a way to redirect backup traffic from a client via a separate NIC, so naturally I thought REQUIRED_INTERFACE would do the trick. However, in reading the admin guide, its not clear whether it is a supported parameter, with the new REQUIRED/PREFERRED_NETWORK settings that are available.

Also, is there an NBU log that would show that the backup connection is using the appropriate interface? I know you can check the stats on the client side during the backups, but I don't have access to the clients. And on the media server side, all the data goes to the same interface, regardless of which nic the client is sending the data from.

thanks