heh, I thought of a funny item (related to this)
item:
specticles (or bifocals, or something similar): increases research by channeler by +5%
It would be nice if you could upgrade the research of your channeler as well as cities. I imagine that cities ultimatly are going to be your main resource and income source no matter what you do, but a very powerful channeler should be able to at least be comparable. He could also have improvements that directly relate to the city he is in, at which point I'm not sure who would be credited for the research (say he has the "traveled scholar" trait, and he gets a bonus for every library with a connected trade network with the town where he resides.)