So now I'm running with this:
#showtooltipYes, I've lopped out an Arcane and a Steady - it has to do with getting a Chimera Shot off roughly every time the CD is up, in order to try to keep Serpet Sting up. There's something like 11.5 seconds of cast time and global cooldown in that - it won't keep Viper Sting up, but I couldn't do that, anyway. Scorpid's even longer than Serpent, so I should have no trouble with that. Kill Shot doesn't go off as often as I'd like it to (when it's lit up) - I probably need it before the cast sequence, but I haven't thought about it while logged in to change it.
/castsequence Steady Shot, Arcane Shot, Steady Shot, Aimed Shot, Chimera Shot, Steady Shot
/castrandom Kill Shot
I'm still pushing only about 1300-1400 DPS on bosses, but I'm still mostly in level 70 gear, and just got the gun off the last boss of the Halls of Lightning, which is where I last watched my meters. Once I'm not wearing a mix of level 70 arena and badge gear, I figure I'll start seeing my numbers creep up more. (And once my crit% is back over 30%, and my hit% is better than a measly, what, 6% with talents now? Meh.)
I still have 3 zones to quest in. Whee.
(Started herbing on my rogue - it has been disappointing so far. I've found... 2.)