As top10 DH on the Hardcore I could say that Bola does much more damage and Hungering Arrow. I don't get why people keep using HA. I was using 2 skills lots of times and finally I chose Bola for myself. If you wanna faceroll with Hungering Arrow (standing with shift and left mouse button pushed), you had better choose this skill. If you wanna do more damage, choose the Bola shot, cuz it actually does imba damage if you use it properly. How to use:
Bola shot with 20yard rune will explode in a second, but If the mob is killed earlier, it will explode exactly when the mob is killed. If you have 2-3 stacks, only 1 will be exploded. You can you this benefit to do mass damage.
If there is a pack of mobs, you shoot 1 time into the first mob, trying to choose the mob with the lowest health, then in 80% you will be able to shoot into the second mob without any movement. When you attack a pack they will start running to you, so sometimes you will need to move to shoot the second target. What happens next: If the pack has low HP, they will die in one second, cuz when the first bola explode, it killes the first target and the second target, so in one second you have 2 bolas exploded. (which will cover more the 20 yards, cuz the first mob will be closer to you, cuz he started running to you earlier, it will explode the second mob which is behind). If the pack has more health, the first bola will damage the pack and won't kill anybody, the second bola you must shoot in the same target, the third bola in the second target. Many ppl say that it's difficult to use Bola, cuz when you shoot the first one, the mob begins to run to you, so you can't shoot another target. Nonsense. What for you have the Vault? With Bola you must hit and run, if it's really difficult to hit the 2d target, use Vault. In theory you do 2-3 times more damage than HA, but actually in 90% situation you need to hit the first target two times, and one time in the second target, cuz one of the bolas can deal noncrit damage and it wont kill the first target.
The second point of using Bola in party is that you usually don't have to wait for Bola to explode. The mobs with lowest HP will be killed very fast by AOE or direct damage.
I am doing cm2 runs, usually running in the front of the party. Sometimes party doesn't even have time to use their skills, cuz 2-3 bolas is enough to kill a pack of mobs (depends on the party).
The coolest thing, that with calamity you have 2.0+ atack speed, so you can shoot 3 bolas untill the first explode. So with a good damage you can have 3 bolas exploded in one second.
It's kinda difficult to explain the mechanics of doing massive Bola damage, but you should try it by yourself, you must fell it.
P.S. I really don't get why this guy is selling this "top quiver" for 2 billion:
http://forums.d2jsp.org/topic.php?t=67887831&f=179I bought mine for 200kk. His top quiver gives me only 5k EHP since I am losing 300 dps. 1800kk for 5k EHP. Lol.
My DH:
http://www.diabloprogress.com/hero/deadmoon-2280/DeadMooNka/28012908