I think the dungeon crawler [dev1053] needs to have a few things to be a success:

notorious monsters unique to event
6man maximum
designed for lvl 99 players
gears unique to the event that can be upgraded
additional drops for upgrading gear
instanced event

Now here are things that i think would make this system AWESOME:

Randomly generated floor layouts
Maze like floors that make you feel like you're exploring
Coffers and ??? NM pops and locked doors (keys drop that floor, etc)
Secret tunnels
Difficulty setting