Although the literature studying software development methodologies (SDMs) lists several significant positive effects of the deployment of SDMs, investments into SDMs by the enterprises remain relatively limited. Strategic investments decisions, such as SDMs investments, are mostly taken with the goal of improving enterprise performance. In this paper a model for evaluation of the adoption of SDMs that focuses on the abovementioned SDMs impact on enterprise performance is proposed. The model was empirically tested in four case studies in software development small and medium enterprises (SMEs) in Slovenia. The case studies confirmed that the use of the proposed model enabled SMEs to improve SDMs related investment and adoption decisions and enabled SMEs to invest their limited resources in the most productive and competitive way. The case study experience with the proposed model suggests that its use would also bring similar benefits to larger software development enterprises.