I've been working on my Anima for the past few days just because I want to finish it up before SB comes out. My reasons for it are mostly just that I want to clear up the quest and see the rest of the story to it, as well as have a weapon with my preferred stats for once, rather than how every other weapon always seems to have one thing that's either pointless or less effective. Ultimately, the decision of whether or not the grind is worth it though is up to you. Stat wise, it'll probably keep you until the 65-67 range as others have stated, and will likely be able to be traded in to skip the first step of the next relic, but at the same time, that first step is usually fairly easy and you can likely get decent weapons for your main class as you do class quests and side quests in SB, and that's not even considering dungeon drops......