Do we really need a third tier of March?
Anyway, atm I think I'll keep 5/5 on both Troub and Night.
Adventurer's Dirge doesn't stack beyond the -enm cap, so it sounds just as useful as Animus: Minuo.
Foe Sirvente is a different thing, it's a potentially useful song but with the current state the game is in, I don't see many situations where you'd use it.
Now if we still were back in the old days there would have been a bunch, but in the days of abyssea and voidwatch would you really use Foe Sirvente?

I guess we have to keep an eye on it for the future, if new content is added where such a song could be useful, I'll just go 5/5 on it, and spend the rest in Night and Troub.