With this app you can easily backup your EFS (IMEI) and modemst partitions. You can backup in Internal and External sdcard that best suits you. This app backs up your EFS in two different types and in two files. First backup is in .img format and second is in .tar.gz format. Alsothere are two backups of EFS at same time. One backup is named as efs_vinny.img and second in efs_(date).img. This wayyou will be 110% sure and risk free. Also there's Successful and failed status of backup.
Note-You can request your model if it's missing in the list.