So I got home from work and did this....
Using the gunslinger class, make sure your agility is maxed out and you have the "Higher Jump" selected. having a weapon equipped with a +2 agility perc is helpful.
Make sure you jump off the rock as the weight of darkness is disappearing. Time it and hold X on your second jump to ensure the maximum amount of height gained from the jump.
It's been done with warlocks and titans as far as I've seen. Hope this helps for the Hunters out there.
Here's my second video that shows the rest of the abyss part
http://youtu.be/J-g-gsyHS6M
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Or- you can just walk through it with blade dancer using shadow jack and blink strike a lot quicker as you won't be shuffling along under weight of darkness. You are welcome.