I wonder if it would work in a raid dungeon, cause as long as the lowbie is not in a raid, and tags the mobs, he'll still get full xp when the other 39 people kill them.

Nevermind. If they fixed it, I guess it's back to regular boosting. You still get xp as fast as or faster than questing/grinding, with the added bonus of not getting ganked, or crowding at a particular spawn. And you can boost in outland in slavepens with a grp of 4 70s and a 55, and the 55 would get just as much xp as a 69 would, but 70s, especially geared out 70s should be able to tear through a lvl 62 instance like nobody's business.