The improvements that I had in mind that you should consider are discussed in this thread:
Currently, once a person has access to a doc, the have access to ALL of the information in the doc. Traditionally, this has been one of the biggest reasons to split docs apart. As you can see in the image below, the end-goal of the current project is to be able to share a page, and the recipient has access to only the information on that page.
They are releasing pieces of the functionality as it makes sense, but we (and I think they) do not have a clear picture of when this will be available in full. To a certain extent this involves putting limits on the linking between information objects in Coda, where a a fundamental part of Coda’s design is the ability to be able to link just about everything to everything else.
In a sense, Coda is doing the opposite of what traditional software companies are doing. They started with individual docs, that could not talk to each other at all. Now they have to develop ways for excel, word and access to share pieces of information. Coda started with a single doc, and now they need to develop ways to ringfence portions of the information in the doc.