Nice guide and good streams.
I've been rolling this spec for about a week and enjoying it. I've been having a hard time with healers. Are you seeing the same thing? A fight with a heal spec operative takes about 12 years.
Generally an unguarded healer = free kill. Operatives are the hardest to kill and good ones can waste a lot of your time but you shouldn't really have an especially "hard" time killing them, per say. That said, in warzones you shouldn't be the only one attacking a particular target, use focus fire. And even if you can't kill a healer they should be forced to run away from you/heal themselves, so that's always good regardless.
Which one of those specs would be best to level with? I'm presently 32 on my Assassin and I'm doing warzones as well as questing.
Doesn't really matter leveling isn't hard. If you want Deception use Khem Val, otherwise you'll need to wait until you get Low Slash before you'll be able to use Maul with any consistency.