As of yesterday on PTR, the dualspec seemed to work correctly, except for 1 little thing.
Specs are supposed to not be changeable when in combat, but on my druid last night i was able to change from balance -> resto as our healer died, by shadowmelding in the middle of the boss Thorim fight, simply by shadowmelding and starting the specchance process instantly the second i got the shadowmeld buff.
It put me back in combat but didnt break the castbar of the spec change.
Suppose this works with rogues/mage invis too, tho i havent had the chance to test.
Helped us immensively on both Thorim and Freya so far.
Balance for aoe in gauntlet and resto to heal on boss
I havent seen this posted elsewhere, and dont have access to elite, so praying for this to not getting fixed
Enjoy while it lasts.