They give almost no exp. I actually tested the level 175 dungeon vs the level 50 dungeon.
The level 50 dungeon has a higher mob count and they give about 4000 exp per kill (600% party finder bonus + 30% from token).
The level 175 dungeon has less mobs, and they give 4500 exp per kill (600% party finder bonus + 30% from token)
In terms of exp gained. 160 Dungeon < 50 Dungeon < 175 Dungeon < 115 Dungeon < 130 Dungeon < 145 Dungeon.
Seriously, what’s up with that? Did someone screw up with the exp values or something?