I'm going to start backing out slowly now with respect to specific "next steps".
I think an important goal has been reached. The basic building blocks are now set out, and through just the first week or so of this thread, I think it has been shown that these blocks can sound great, even when put together in the most basic ways.
The more general "next steps" are to refine understanding and use of these building blocks, and how to further manipulate them to match your desired model and future goals when you feel comfortable moving beyond existing models.
I would love to keep chiming in on the technical aspects though. In particular there seems to be gaps in many basic descriptions of what is going on within a room or an artificial reverb.
The modal density question is a good one. Knowing what defines it in an artificial reverb is the first step to knowing how to control it.
The modal density is the superposition of the frequency response of all of the feedback and feedforward paths in the recirculation part of the topology, excluding the ones within any allpasses.
What defines the recirculation part of the topology?
What defines a feedback path, and what defines a feedforward path?
I mentioned earlier that having a balance of both types of paths is a good thing; why is this?
-Casey