At the recent IWSM in Beijing, one of the most impressive presentations was from Dylan Ren of Measures Technology LLC, which described the excellent progress being made in the use of COSMIC in China. His presentation is available here. (There is enough English explanation that the messages are clear even if you cannot read Chinese.)
One of the most interesting slides is #11, which shows data from two companies. On both graphs the x-axis shows size in units of CFP and the y-axis shows effort in units of man-days. Each dot represents the functionality delivered in a release by a team in one month. The dots of the left-hand graph are for work on different sub-systems of an insurance company. For the right-hand graph each dot represents a different project in that company. As in both cases the delivered size consists of small new additions as well as modifications to existing functionality, the size/effort relationship is surprisingly good.