I think it will also depend on your level relative to the others in your party. If you are level 32 and everyone else is level 25, you're not going to get much experience. And if you're level 25 and everyone else is level 32, then you can get halfway through a level or more. But it gets worse as you level up--I have heard that the 50s is especially bad for LDoN experience, perhaps less than 10% of a level per adventure. But that's only hearsay, I just dinged 50 myself, and at 49 I did a LDoN and got about 30% experience, which I was pretty happy with.
At low levels, LDoN is mostly about the experience and the money loot (you can do better on loot, but generally not while getting the same good experience). At high levels, the item loot is pretty good, and the money loot is okay, but the experience isn't as good. However, at high levels you actually get a decent amount of points per adventure, so you can afford the LDoN items which are actually decent but require lots of points to buy.
Game on,
The Oneiromancer