I like the idea, especially if it's completely optional. Low-level dungeon queues can be extremely slow, and having a few level 80 players available could make leveling feel much smoother for new players. sprunki
That said, I'd also keep some incentives fairly small. If the rewards are too good ...

Yeah, addons help a lot, but on private servers timers can be a bit inconsistent.
What I usually do is just note the time when I or someone in chat kills the rare, then come back around that window. Also camping during off-peak hours helps a lot.
Curious if WoW-Mania has slightly different respawn ...

I usually pick one expansion per week and clear everything with a high-mobility class like a Druid or DH — it makes farming way faster. sprunki
Ulduar and Throne of Thunder are my go-tos for unique sets, and Firelands still has some of the best glowing weapons.
Simple rule: more alts = more loot ...