I was thinking that, but I only want to build one (maybe two) limited healers if I can help it. I don't want to dedicate gold orbs to standard Himiko since she's a general pool character, so I'll probably get duplicate copies of her naturally over time. Both Summer Himiko and Christmas Arthur and Himiko offer different things though, so I'm finding it difficult to decide.
Summer Himiko brings an AOE heal for 2BP that also reduces the wait time for the targets healed. She can also give an AOE Encouragement buff (cross shape) and 50% damage barrier to her allies. The downside to the former is the cast time, which is pretty slow. It's an AOE heal which is nice, but if I need my character healed right away it could be an issue in more difficult content/arena.
Christmas Arthur/Himiko on the other hand only have single target heals but they're a lot more potent than Summer Himiko and the cast time on them is virtually half so you get them off much quicker. They both add an ability buff to their heal as well, which kind of makes up for them being single target. Christmas Arthur and Christmas Himiko both give Encouragement to allies with their third ability (similar to Summer Himiko), only instead of the shield she offers they give your allies immediate action so they can act right away (which could be helpful in picking off weak enemies in the arena before they have a chance to respond).
I saw that Christmas Arthur was guaranteed at the fifth step in Japan, so I'm thinking I may wait and hope Nutaku releases her banner outside of the season. If they go in the order of banners released in Japan, so she be shortly after Achilles (so around two months from now). That's assuming they don't delay her for six months to sync us up with Christmas, but I can't really see them doing that since it'd throw everything else off. The potential is always there, though.
I'll give it some more thought and then decide. :/