The difference between covenants will no way be as insignificant as the difference between racials. Maybe i'd give them the benefit of the doubt if Soulbinds were class specific aswell, so they could balance each class' soulbinds compared to their abilities, but they're not and I somehow doubt something like Abom Limb which has utility attached to it will ever come close to DD in throughput, even though said utility is only useful in a small handful of scenarios.