Modeling benefits and Quality of Service (QoS) for Multi-Service Architectures (MSAs) is important to enable service providers offer the best Transport Telematic Services (TTSs) with high societal benefits to users. This study models how different QoS characteristics may influence potential benefits of MSAs for road based freight TTSs. This is achieved by modeling the QoS degradation under conditions of shared resources and including costs associated to such degradation to determine the benefits as the difference between the costs and societal value of the applications. A system performance oriented QoS measure has been introduced in coming up with a MSA benefits model, providing a possibility to capture different quality attributes, desired performance levels, and even the possibility to introduce desired priorities between applications and quality attributes.