dont those go up with how much xp you get .. so double xp kinda is a bonus to those right .. at least the earring quest .. maybe not the others cause they req hunters and stuff .. but then we also got faction/double rare named spawns ..
correct - easy way to make this work would be to add a Evolver XP "tablet" to all mobs loot tables in ToV and or TBL that you could Right Click for a % this is how they did it for the tear aug.
Evolving Item XP doesn't work the same as Normal XP. The xp bonuses have no impact on evolving item XP. They are calculated based on mob con and how many people are in group, whether there's an XP modifier normally or as a bonus there's 0 change to the evolving rate.
I like your thinking on adding in items to add experience to evolving items like the Tear of Alaris had, I would guess that the devs did not take that route on purpose though so the chances they will do this is small, not impossible though.
Evolving xp bonus as nice as it would be isn't likely, what I would like to see is a bonus to group mission currency.
Around this time would be the perfect time to add them. 3 months till the next expansion (impatiently waiting).
They could toss it in as one of the Overseer reward options, much like Merc AA XP. Might be something to actually entice people to use Overseer more.