I think Traya + Sion is really a necessary set of zetas.
The two by themselves can take out an entire Geo squad, it’s an extremely efficient investment and utilization of resources. If you have them geared and zeta’d and your opponent places Geos on D, you have an eaaaasy win. If no Geos, then Traya is still one of the best toons in the game, and an offensive juggernaut that will clobber most any other team. Solid investment still.
Also, very few guilds are doing LS Geo TB. Traya + Sion are a great core for full clears in DS Geo TB. I think there’s more immediate utility for you with these two.