I know about the EML, but number of shots is not really an issue for this army - range and high S are more useful. Once in the template kill zone the Wraithguard are almost certain to wipe whatever they shoot at.
I used the Shadow Weaver option because it is cheapest and has double the range of the D-cannon. I love the D-cannon, but as with the EMLs I need to mitigate the short effective range of the bulk/core of the army. In a more defensive army I would certainly use D-cannon platforms though because you count on the enemy coming towards you, and into range of your barrage.
All that is important is known.