Larian Studios Forums Divinity II The Dragon Knight Saga / Flames of Vengeance (English) Divinity II - The Dragon Knight Saga Fjords to Aleroth - Transition sooner or later?

Yes, towards the end of the fjords it isn't really necessary, but then it is useful in the Hall of Echoes, and you'll need it again at the end of FoV.
I never had a problem with mana in dragon form, so was never tempted by the +40% Mana dragon cuirass. Half way, or so, through the fjords I removed all dragon armour, then ran into a problem with the Hall of Echoes (difficulty bug, worked properly the next day) and re-equipped it.