Ya, BM's AOE has REALLY come into its own after a few tweaks. Survival still reigns supreme because of the utility they bring with traps, but frankly, serpent spread is only as outstanding as it is if the dot is ticking multiple times. Don't those mobs you are farming die in like 2 hits? If they are up for 20-30 seconds after spreading, then it will likely be more DPS. Otherwise, BM might be the best option, as you can have good burst, and plenty of CDs to help you.
I did it as Survival, because it seemed like my pet kept dying to the DoT and Serpent Spread procced the Singing Crystal very frequently(and ticks very, very hard if you get a book proc + have Chi-ji shrine buff)
I don't really think spec matters much, the main thing is just spamming Multishot and having the different buffs active while doing so(Chi-ji Shrine, book, crystal and maybe dew if you get hit for some reason)
Also WTB TED. Stupid RNGesus. Never gonna see it till after my guild kills H Garrosh 25 for the first time. I wanted to at least try BM a couple of attempts. /sigh
Haromms is still decent for BM because of how good it is, and how shit TED is.
I've been marks up to 82 and just went survival and even though Marks still has more burst for low health quest mobs, survival is better on aoe and for dungeons I think. I was still one shotting mobs with chimera shot all the way up through Cata. I guess I'll test both at 85 when I get to put on my archeology BoA gun, lol. Absolutely loving the class, such a high skill cap. Have about a billion macros already and a ridiculous amount of keybinds.