As of now, if you attempt to travel backwards over an obstacle, you will always fail it regardless of your agility level. (If you fall down by trying to go backwards you will now only take minimal damage.) This was necessary to stop players from taking advantage of an oversight where it was possible to gain a better rate of XP by simply traversing back and forth over certain obstacles rather than attempting to get to the top.
On Monday we were forced to alter the XP rates for the affected obstacles; the original higher XP rates for all the obstacles have now been reinstated. You will now gain exactly the same XP from the pyramid as you did when it was initially released, and as a useful side effect it will be a lot easier to give up and escape the pyramid if you find yourself running low on food or water.