Probably quite the opposite. I know enemy AOE assumes you're facing the mob, so I'm guessing it also assumes they're facing us.
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I've done T5 with Elfin Bow, putting me at around a mere 440 accuracy, and it didn't significantly cost me dps. In fact it's usually slightly increased it, but at the potential and just slightly fearsome cost of missing against Conflags [moving to the north side can fix that] and Deathknights [usually flank]. If you have to sacrifice upper level (no-accuracy) accessories to equip though, save yourself the bother and use the Zenith. You can often get one more ability off under Raging Strikes / BFB benefit with Zenith's skill speed increase that would be impossible with Elfin, depending on your accessories.
It's definitely a dps increase to switch for T1 and T4 where you can better benefit from multiple target's worth of DoTs and subsequent Bloodletter resets (both snakes, both knights, both rooks, and so forth). Since there's no such benefit on Turn 2 and you have the possibility of missing a silence, it's best to stay capped for that.