Just spent an evening in the hopper caves. 43 SK, 44 Cleric, 44 Bard, 50 Paladin, though two of us dinged toward the end. We fought our way through to the back, and were able to keep the age-old's room cleared as well as the larger room outside. Went through maybe a dozen spawns before giving up and heading out, but then the bard spotted the age-old on track -- it was the next pop after we gave up! So we went back and killed it, but got only a medium quality hide and Navi's bracer. (We were also hoping to find Gant's Remains for another quest.)
So this looks like the standard quest: hoping for a rare drop from a rare spawn. But it was good xp, and the hides bring good money in the bazaar, so we'll probably be back to try again!
Edited to add that the age-old was red to 44 and blue to 51, so it's definitely not limited to level 46. (Our must've been 47-50.) It seemed immune to the cleric's Pacify (supposed to work to level 55, so it must be a mob special ability), but we managed to single pull it and had no problems. Then bard-speed to run out of the caves before the tribals popped!
Edited, Tue Mar 7 03:42:23 2006