Kej?

Is there any reason to keep all the Kej from Azj-Kahet that I've acquired or am I better off converting it all to Resonance Crystals at 2-1 rate for at least buying housing stuff? I can't find anything in the area that I'd still need short of a few thousand for alts to buy the crafting books. Between too much time and too many alts, I'm drowning in the stuff.