b) I would feel it really odd that CKAN models weren't in ckan.model. That would probably break a lot of stuff. If you don't now anyone that might need this now, I feel it would be better to keep it as it is.

b) But that works with this code. I only raise an exception if you call something like ```model_name_to_class('okapi')```, throwing an exception because there's no ```ckan.model.Okapi```. It doesn't check if the user exists or not, just that its class does.