I published this post on architectural granularity just over two years ago and have been made aware of a research paper published on this topic last year: Weber, M.; Wondrak, C. (2012) Measuring the Influence of Project Characteristics on Optimal Software Project Granularity in: Proceedings of the 20th European Conference on Information Systems (ECIS). The people responsible for the paper are working on a web-based service to make the tools from the project available for software architects. You can find a preview/demo here.
Topping off the tank
15 hours ago