i think it's generally accepted that wind is, in fact, more accurate than string, hence why lullaby is usually cast in a mary's horn instead of a nursemaid's harp.
i cast requiem on omega. not that it really matters much anyway. i also get resists on elegy on omega, but not so bad that using battlefield and carnage whenever they're up doesn't suffice.
honestly, i would merit everything else before doing 5/5 night and troub. i have one in each, which is good enough for what i do (i'm usually on whm). but if you do a lot of sky, and you're always on brd, then i guess it'll save a bit of time, seeing as you don't have to wait a bit to pop the next god. it'll also help if you ever need to ES troub elegy more than once in a fight.