Hard to say whether they'd be upgrades or not since no one really knows how Singing/Wind compare to straight magic accuracy.
We would need further tests, no questioning that.
Last I read, which is a long time ago, it hinted at Sing skill being pretty close to 1:1 (maybe 1:0.9) and wind/string being 3:1.
String has the additional bonus of potentially granting further tiers for range on songs you cast with Harp.
For buffs it's hardly relevant, you autocap 19.9 yalms range on the majority of songs. Exceptions being Ballad3 and... Minuet5 maybe? Probably something else.
It's not really that important there anyway I would say, although it can *** you up if you're singing fakes thinking you will hit that friend at 19,5 yalms range only to see him receive just 3 out of your 4 fakes...
Regardless, where it matters is for Horde Lullaby. You would want Brioso+3 head there I think.
And that's not a big deal since you don't use 5/5 Brioso for Lullabies anyway, well at least in the duration set.
I don't think any Bihu is a valid replacement for Brioso+3.
Even without factoring the +15 macc from the set bonus I think Brioso is always better.
Closest you can get is on legs (~95 total macc vs ~96, considering 1:1 for Sing, 1:1 for CHR and 3:1 for Wind) and second best is Head if I recall.
It's a shame but the macc bonuses we received on reforged relic have been lower than expected on pretty much all the pieces, even for other jobs.
I think reforged Fili legs+3 is a good candidate for use in place of Brioso+3, they would have to *** things pretty hard to make them worse than Brioso+3 w/o set bonus. In before they succeed lol!
Anybody ever tested the Song delay- gear btw? Like Fili legs.
I think those seconds are subtracted before everything else, and then Fast cast/haste are calculated on the reduced value, but that's just my assumption since I never tested it nor seen tests performed by other people.
If this is true the relevance of those seconds would be much lower than one would initially expect.