Early G2's had an issue with losing EFS, the encrypted area of the file system where your IMEI and country settings are located, especially in early international variants. It is a good idea to maintain a backup, although not necessary, where it could come into play is if you accidently flashed a ROM for a different variant, it could corrupt the EFS partition.
It is possible for other issues to corrupt the EFS partition... Early on I was running a custom ROM and looked down at my phone and it showed I was always roaming for some reason... nothing I did would correct it, restored EFS and all was well again.