You're welcome, all.
As predicted, I have already made significant improvements to this framework, even just since it was released. It's amazing how much easier it is to create dialog boxes when I can drag "Select Alignment" and "Select Profile" controls onto a form, and they just work with no further coding.
I feel that creating a full Software Development Kit for Autocad products would be incredibly useful. The frameworks I released on the Quux website illustrate the basic idea, but they need a lot of work before they can be considered "complete". And of course, the idea can be expanded to all of Autodesk's products, not just Civil-3D. So there's lots of potential, but also lots of work to get it done.
If there is sufficient interest, I can look into getting a full Open Source style project up and running for this development. But that basically depends on the interest in the community. So far, I have had spot interest in such a project, but it seems most people don't want to work on Open Source projects. So if you are interested in such a project, let me know. If there's enough interest, I'll look into breaking these frameworks out into a full-fledged Open Source project.
Otherwise, Quux Software will most-likely continue to release a core Civil-3D SDK as it develops. The "old-style" of customization we've historically used is just too painful, so we view it as important to spread the knowledge that there's at least one better and faster way to do things. That's assuming we can get something working along the lines of the Ruby on Rails model, where a company releases much of its core development kit for free, in addition to offering premium products and services at a cost. Of course, such an effort would not include SDKs for the other Autodesk products (since we are a "Civil-3D Only" shop), the SDK documentation will continue to leave something to be desired, and releases of improved kits would be more sporadic in such an effort. But at Quux Software, we view support of the community as a high priority, even if we could improve our competitive advantage by keeping all these ideas "secret".