In theory, re-rolling makes them the best in the game (Destiny)

by iconicbanana, C2-H5-OH + NAD, Portland, OR, Tuesday, January 13, 2015, 16:24 (3400 days ago) @ slycrel

Being able to reroll a 331's perks for just 2 motes is a pretty sweet deal, and can potentially create some pretty sweet perk-packages. The inability to upgrade them to the new next expansion's attack rating takes away a lot of that potential; you end up spending a bunch of motes on a gun that ultimately will be obsolete in 2-3 months.

Still, it's a chance to create your own field scout / firefly / zen moment monster scout rifle, or crowd control / explosive rounds / clown cartridge hand cannon. I don't have the perk tables in front of me but you get the jist.