User Centered Design processes argue for user testing in order to assess and improve the quality of the interactive systems developed. The underlying belief is that the findings from user testing related to usability and user experience will inform the design of the interactive system in a relevant manner. Unfortunately reports from the industrial practice indicate that this is not straightforward and a lot of data gathered during user tests is hard to understand and exploit. This paper claims that injecting results from user-tests in user-tasks descriptions support the exploitation of user test results for designing the n+1 prototype. In order to do so, the paper proposes a set of extensions to current task description techniques and a process for systematically populating task models with data and analysis gathered during user testing. Beyond the already known advantages of task models, these enriched task models provide additional benefits in different phases of the development process. For instance, it is possible to go beyond standard task-model based performance evaluation exploiting real performance data from usability evaluation. Additionally, it also supports task-model based comparisons of two alternative systems. It can also support performance prediction and overall supports identification of usability problems and identifies shortcomings for user experience. The application of such a process is demonstrated on a case study from the interactive television domain.