Currently, in my current gear (ilvl 499 enhancement), on single target, i gain 5k dps with EM over picking no talent and 5.7k for EotE.
Cosidering that in it's current state, EM up time would be doubled, it's no question that EM will win. It will be the same for elemental.
For now, even Ancestral Swiftness would win over EotE by some margin. Currently, it's a 3.9k dps increase for me. Not using the instant cast is a 700 dps decrease, so the 5% haste make it a 3.2k dps increase. Doubling that part makes it a 6.9k increase, which would be better than EoTE.
Expect EotE being taken only for AOE fights. I hope they rework enhancements AOE since it's totally bad without EotE.