The reason you might wanna go for narmer isoplasts over exploiter orb farming is A) you are solo and can't do exploiter orb quickly or B) you want to be farming other things like caliban's parts or the new mod sets at the same time. I'm SURE you don't have all the new narmer mods yet, there are a set of 3 for each archons: 3 for Nira, 3 for Amar, and 3 for Boreal. Plus each has one weapon too so yeah. Lots of narmer bounties farming these new things=extra isoplasts for rep.