Lategame Dunban Arts Builds: Serene Heart vs. Spirit Breath

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So hey, anybody that knows Xenoblade:

I’m trying to make a versatile Dunban Arts build, and I only have room for two auras, given that I‘m allotting five slots for physical arts (topple combo, Worldly Slash, Soaring Tempest), and one slot for Blinding Blossom to shift aggro. While I like Serene Heart because it’s dodgy, I have Dunban’s agility high enough that the benefits I get from being able to dodge more are rather slim at this point in the game. Everybody says Serene Heart is better, but I swapped it out for Spirit Breath, and enjoy that much more with Critical Drain et al linked to Dunban, even though Peerless is also a damage booster, and the two skills are mildly redundant in their purpose (Peerless increases damage output, Spirit Breath adds haste).

My current setup is as follows:

Gale Slash
Worldly Slash
Electric Gutbuster
Steel Strike

Soaring Tempest (gotta fill that Talent Art)
Blinding Blossom
Peerless
Spirit Breath

So my question is: Is the added debuff removal from Spirit Breath worth keeping it over Serene Heart, which makes Dundun dodgy with no added side effects? It seems like a panic button that has no place in normal fights, or fights that are manageable, since if Dunban, the primary tank in my setup, needs the extra agility to stay alive, then maybe he’s fighting something he shouldn’t be. Serene Heart takes a few seconds to activate, seconds that could be used to attack something and get in some extra damage, but it seems like it could be used effectively in a strategy that focuses on drawing aggro first and then playing aggro sponge while others beat on enemies, like this, for example:

Peerless --> Gale Slash --> Electric Gutbuster --> Steel Strike --> Worldly Slash --> (move into center of enemy cluster) Soaring Tempest --> Serene Heart --> Blinding Blossom on the first monster to attack somebody else

After this series, I should have a full Blossom Dance to unleash on the strongest enemy in the group.

I understand that trading Serene Heart for Spirit Breath ups his DPS at the cost of his survivability, but only if you stick with auto-attacks, making him a monster with Critical Combo linked to him, but that makes it so that your other Arts are only useful for Topple and Bleed. Meanwhile, Serene Heart would help him hold aggro since aggro goes down only if enemies can hit Dunban (he dodges more than enough without it).

Alternately, I could dump Worldly Slash and just go for that third aura until I get Dunban's final arts.

How do you all build him?