Here's what I say. Keep the Exotics and Raid gear upgradeable. I can part with the rest. As much as people farm for, say, Hopscotch Pilgrim, it isn't nearly as bad as the farming people do for raid gear. I still farm for Hunger and Word of Crota as well as the VOG shotgun. I think that exotics and Raid gear stays so old Raids don't go obsolete and exotics because exotics.