The contributions of this research are briefly described as follows: an evaluation framework for model composition effort; practical knowledge about the values that the composition effort variables assume in realistic composition scenarios, i.e., the quantification of the required effort on applying the (semi-)automated composition techniques, detecting conflicts and resolving the emerging conflicts; the identification of specific scenarios of evolution and factors that lead the composition technique to success (lower effort) or fail (higher effort). We also summarize some interesting findings: the higher the number of overlapping parts of the input models is, the higher the composition effort is; conflict propagation between the model elements has a negative impact on the developers' effort; sometimes developers prefer "living with conflicts" instead of spending effort to resolve them; and the resolution of unexpected conflicting changes is influenced by the developers' reputation in the software development team.