Guess I wasn't being clear about the 'EFS'. People want to backup the EFS mostly for the IMEI, serial, etc. But on S4 mini the IMEI is stored beyond the simple NV.DAT under the EFS folder. Guess they either try to protected it hard from being corrupt or changed. Either all EFS folder backup isn't sufficient any more for IMEI backup. I've already messed up my serial when trying F4k's early Slimkat build, which I could easily restore the serial on the S3 but not the S4 mini...
To conclude, it quite defeat the purpose of having a 'EFS' backup.
Okay ! Thanks to you for the explanation because i was totally un-aware of that
Have a nice evening
Tapatalked from my TF701T