Lightweight software development methodologies promise an easy way to deliver products of high quality without excessive cost. On the contrary, classical heavyweight processes are well-defined and proven, but require a lot of effort. Two approaches: eXtreme Programming (XP) and CMM Level 2 have been used in joined industry-academic software projects run at the Poznan University of Technology. Running concurrently those two software approaches allowed us to compare them on the basis of experimental data. After the projects were completed, major risk factors connected with both approaches have been collected and some improvements have been proposed.