I agree with the Great Idea comments, although I'm not sure how easy it would be to differentiate this from the NM based Levequests. Perhaps simply split the NM quests out into their own 'Hunts' section?
Example: Each levequest timer refresh, 1 Hunt per level range is offered, (e.g. 1-20, 21-30,31-40,41-50). Hunts are given a 45 Minute timer from their start at the Aethryte and the players are given some small clues on things like location to find the monster/how spawn it and maybe a few simple tips on fighting it.
Another possible issue would be players going at these with 15 player parties in order to just zip through the quests for Loot. The best way to probably solve this and also make the Hunts memorable and challenging would be to impose a maximum party size and limited difficulty settings, say 4 or 8 man party size cap and 2 difficulty settings (Low and High). This would hopefully encourage smarter play rather than just dumping a lot of players at the Hunt Bosses for gear.
It's inevitable some guides would come out for the Hunts, but a small element of randomization (such as location or precise spawn conditions) and such would probably keep them from being too bland after they've been out a month or two.