I am glad to hear that you are open to new ideas. As someone who worked in this field for a long time, I have developed some ideas about 3d app interfaces and work flows based on my past experiences and struggles that I tend to think that would benefit users. I will dig in the Wiki and see where and how I can add some of my thoughts.
I have seen the Pipeline panel, I see where you guys are trying to go with it. As you have mentioned it is rerendering a pipeline that is in place already. I think that for viewing purposes it might give user some perspective on the state of the document, but would there be any direct help, I am not sure about it. When it comes to node based approach there are 2 examples, one is Maya and the other is Houdini. I definitely go with Houdini because it is designed that way from ground up and it does not feel flakey at all, it is also very functional. I can see that K3D achieves some of the Houdini flow without needing the visual graphs, so that is really positive to me as a user. In the end K3d might not need graphs if we can find a different approach. I would personally like to see a node based system, but a node based system is only one of the approaches really.
Couple years ago I created a personal proposal about shortcuts in general for Blender(prior to 2.5), but they have taken a direction at the moment. So I am thinking to resurrect and revive that one for K3d. I will bring it into conversation over the weekend.