I think it may be good for a farming build, but not a big deal.
50% Double Strike (1 Slot, Demonic Bonus) = 2x Damage (Almost)
60% MS (4 Slots) = For activating bonus
+ Momentum(5) (1 Slot) = 50% x 60% = 0.5 * 0.6 = 0.3 = 1.3x Damage
Total Damage = 2.6x Damage
Damage Increases per Slot (DIPS): (2.6)^(1 / 6 Slots) = 1.17x
So like I said, it's not a big deal.
It would be even less if I consider that double strike only has 50% chance to trigger.