Okay, based on feedback from sjgadsby and mandor, combined with a verbal conversation with a co-worker, I have some ideas on how to narrow the focus to the essentials and at the same time beef up what's currently questionable.

The best news is I have a way to make both mandor and sjgadsby happy with the main diagram. I'm going to change the nature of that portion to show the infrastructure built piece-by-piece while explaining the rationale. Each piece will be a subset of the diagram, omitting the parts I'm not talking about at that time. The complete diagram will show after all pieces have been presented.

I'm also going to de-emphasize all roadblock points and move them all to near the end.

I was nervous last night about the shape this was taking but after today's exchanges I'm more confident again.

Thanks all!