I also prefer my Laev R15 quite often in Odyssey and Sortie. In sortie, I don't even need to use Vidohunir for AM2 but we regularly kill all 8 bosses extremely quickly. Odyssey is a different story/group altogether.
I personally prefer REMAD weapons for event-based weapons, because I know SE likes to introduce meta/shiny weapons that invalidate the current meta or BiS. (i.e. Mythics have a lot of staying power, but Raetic weapons were hot for a few months, I think).
My biggest concern about Laevateinn, when compared to Marin Staff +1 is that Marin gives you +20 INT differential at the cost of ~5 M.Acc and ~2 MAB. However...Laevateinn has +269 vs Marin's +228 Magic Accuracy skill. That +41 M.Accuracy skill can't be recouped anywhere else but the weapon slot.
So, for me, the INT differential exists, but so far hasn't been an issue for me keeping up or exceeding others, in terms of DPS. Having said that, you'll need to R15 BLM mythic to remain competitive.
Speculation and Conjecture: Now, keep in mind, it's entirely possible that Magic Accuracy Skill+, only obtained through the weapon slot, perhaps improves nukes that land as 2nd-place or 3rd-place in a Nuke Wall Magic Burst situation. I don't know if players can answer this definitively, but I also don't know if it's been tested.
Hypothetically, to be certain of the above situation and to speculate on the effect of +41 Magic Accuracy skill difference, some 2-3 FFXI mathematicians with both weapons would have to do some testing. (At the moment, it is just my made-up guess that I did not base on any reality, just my small amount of faith in SE and some anecdotal evidence).
Having said that, make the mythic but you'll have to R15 it! And congrats on the Cat's Eye! This is a good problem to have. :)