Still leveling my hunter and only things i've noticed is it not using kill shot fast enough, doesnt seem to cancel current cast and use killshot if possible, according to icyveins as mm hunter should just spam murder of crows, chimera shot and kill shot on any target under 20%(only murder and chimera are apparently above kill shot in priority, and kill shot has no focus cost and no cooldown when cast on a target that doesnt die)
This might be due to me being sub-90 though.
Edit: The mm new mastery increases range of hunter attacks, i think this will be highly useful in pvp but also somewhat useful in pve to fire from really long range, hope you can add support to scale or increase the max range for mm hunter!