Within Industry 4.0 many connected systems are entering production to optimize the processes. The integration of the manual workstations into a Smart Factory, as a fully connected production, is required as well. Therefore, systems with which the production workers interact as users are introduced. However, as a side-effect, the production employees and their working performance are more transparent as well. This often leads to a lack of user acceptance, even though these systems have positive effects on complete production processes. If, for unforeseen reasons, there is a lack of user acceptance, the introduced system will not be as successful as planned, irrespective of how technically valuable the future product is. Therefore, the potential user acceptance towards the System-in-Development should be understood. This contribution introduces an acceptance model that has been developed and validated within a Live-Lab with industrial participation, as a research environment between laboratory and field studies. For this purpose, influencing factors for user acceptance of connected products were identified. Based on various scientific surveys, the factors were weighted and their interactions analysed in order to enable prognosis regarding user acceptance and to derive recommendations concerning actions for the downstream processes.