Food for thought. The last 10 or so threads in the Tanya forums have been about Kobu. Kobu guide, Kobu tech, how to stop Kobu, Rekka's too strong ect. Wouldn't that be an indicator of how strong Kobu is?
The thing about Tanya now is she has one reeeeeaaaally good variation and 2 others that are situation and even in those situations Kobu probably does it better. Pyro's zoning isn't all that compared to kobu's 1 projectile.
So yeah Kobu is really all you need because Kobu is really all Tanya has going for her at this point. :/