With the new boost of Exp, someone had a chance of see if those instances are affected directly by vitality?
Maybe its because I have a ton of boosts going at the same time, but it almost seems like vit makes no effect.
There was nothing in the patchnote about those instances getting vitality effect, so I'd assume they don't. No (or almost no) instanced boss (kartia, istina, baylor, ...) takes the vitality in account when calculating xp earned.
Vitality itself doesnt affect the exp bonus from raids, but if you use freya or maphr scrolls you will receive more exp so having vitality while killing the bosses has some uses.