If you just use luma and never do any messing with nand, you wouldn't have issues, i haven't done a back up since installing a9lh and i been golden.Mostly, it's a paranoia thing as a holdover from the rxTools/EmuNAND days. I know that there's nearly no chance of bricking after A9LH, but to my line of thinking, using a RedNAND is a first-line defense against that, since I'm not the most regular person about performing backups.
Luma is the safe CFW so it should be worth it.