Why do you say that? I look at it this way: they accomplished their goal, they dealt with the obstacles, they got out. Avoiding an fight is the best way of winning it! Full XP.
In the example (#6), the PCs completely avoided the obstacles. They didn't "deal with the obstacles". Now, if digging the hole meant concealing the effort from the badguys, or misdirecting the badguys, or holding off the badguys, or something else like that, then sure, they get xp. But if the badguys are *completely* avoided, they don't give xp.
If an ogre is guarding a path in the woods, and PCs walk an extra 3 miles out of their way to avoid encountering it, do they get xp? They may still reach their destination, but they didn't overcome the ogre obstacle. That's how I saw #6.
So if they go through the bad guys, they have achieved their goal - gotten through the obstacle, gotten the treasure. But X is also responsible for keeping them from their goal. So, if they bypass X instead of B, what's the difference? Why give them less XP for taking the smart route and bypassing the tough encounter? That's playing smart!
Well, if they completely avoid B (and I mean "completely avoid", vs. find a way through or around), why give them xp for B? Do you give xp for encounters completely avoided? (See above.)
If they overcome X to get at $, then shouldn't they get xp for X, not B? And what is the xp for 20 feet of rock wall? (And did the PCs overcome the rock wall, or did the sappers?)
And I ask again, for those of you who say you'd give xp for the mcguffin: how do you figure the xp value of it if not based off overcoming the obstacle(s) to getting it?
Quasqueton