I agree with Vinhi. One of the problems faced with getting to higher levels/more difficult areas of a dungeon, when a dungeon such as the UC has such a wide range of mobs where players might be found fighting, is that higher-level players, attempting to reach the areas of the dungeon they'd like to explore, usually run through the easier/lower-level parts of the dungeon. If there are lower-level players in these parts, this could cause quite a problem for them, especially if the higher-level player is running past gobs of mobs, causing such mobs to give chase & run after them.
These lured mobs often, upon realizing that they aren't going to catch up to the higher-level player, happen upon the lower-level players en masse and cause these poor, lower-level players an unnecessary death.
Having a system such as Vinhi proposes would eliminate this scenario and improve overall game play. It also would allow for more flexible dungeons to be created, where the range of level of players that can have "fun" such dungeons/mapsets would be quite wide, indeed.