Calling 7401 or any other BIOS posted by Shamino (and previously Elmor) unofficial is misleading.
Both 7401 and 7306 are official BIOS files from ASUS, they just come through different channels.
7306 is a RELEASE BIOS, which has passed all internal validation and testing at ASUS and has been published to their support site.
7401 is a PRE-RELEASE BIOS, which has passed some testing, but is not fully validated. It is given to us early via forums to give us quicker updates, on the understanding it hasn't gone through the full validation process. There is every chance it will be released in time as a RELEASE BIOS, we're just given it early in the process.