Arena scoring question

It will add more points, but I really wouldn't do it unless you planned to do it anyway.

Aether will provide slightly more points

Aether should give slightly more in the short-term but the merges add up in the longer term even for limited GHB units. I would say the increase to your score from either would be so minimal you probably won't notice unless you're actively fishing for the highest possible score even by +2, so just do whichever one you'll find more utility in. Don't bother with Aether at all unless you definitely want it on his final build(s) though, imo.