Taliafears' bs/ss switching
I have a much larger form going, but I'm still only lv42 so my experience is limited. I do want to share a rather clean way to switch between backstab and sinister strike - check ifTargetOfTarget. If they aren't targeting you, you can get behind them. Also, it seems that while they are gouged or stunned you are NOT the target of your target, so this still works properly.
Also, the "must be behind" message is usually hidden this way (some other solutions I came up with had it popping up repeatedly). It actually turns into a great visual cue when the mob changes aggro. You won't ever see the message unless it's in your best interest to "do it from behind". :)
// PvP players bunny hop and run around a lot, so just backstab at any opportunity
bs-ifNotTargetNPC
ss-ifBehindAttackJustFailed-ifNotTargetNPC
// During PvE this reminds/forces you to get behind the mob when you don't have aggro
// This will help you a lot if you've invested in backstab talents.
// Remember to feint often.
bs-ifNotTargetOfTarget-ifNotShiftDown
ss-ifTargetOfTarget
ss-ifShiftDown