I hear you and I did consider Erie... Her place in disco is a weird one to say the least. I'm not even completely sure that the Zoners have managed to reconcile having a new planet suddenly which is also kind of a Liberty planet and, oh look! Lanes and such.
I dismissed Erie based on the following factors. Note that I'm not claiming that my view is right and yours is wrong, they are simply my views.
1) Liberty does not need more trade.
2) The Zoners do not need routes which concentrate them in the core. From Erie to Ames, for example, is almost entirely within the core worlds of Sirius.
3) I'm not sure if Erie could be considered as a cultural hub for the Zoners, a place for them to return to after departing into the dark.
I'm sure I could dredge up some other thoughts but... Well... Yeah =/
Maybe I'm biased against Erie due to my not really getting it.
