Are you mostly using high status weapons with a high RoF that deal damage over time without Faction mods? Than use Roar.
If your using weapons that have minimal status, low RoF, against mobs with a Faction mod, or have no way to inflict bleeds? Than keep Xata.
Also, Roar doesn't completely fuck up your fashion like Xata does which is something a lot of people seem to care about.
You don't need Ophanim Eyes on Xaku since they already lay down massive AoE strip areas that instantly remove defences and your 4 also inflict a slow.