The problem of channel sharing by rate adaptive streams belonging to various classes is considered. Rate adaptation provides the opportunity for accepting more connections by adapting the bandwidth of connections that are already in the system. However, bandwidth adaptation must be employed in a careful manner in order to ensure that (a) bandwidth is allocated to various classes in a fair manner (system perspective) and (b) bandwidth adaptation does not affect adversely the perceived user quality of the connection (user quality). The system perspective aspect has been studied earlier. This paper focuses on the equally important user perspective. It is proposed to quantify user Quality of Service (QoS) through measures capturing short and long-term bandwidth fluctuations that can be implemented with the mechanisms of traffic regulators, widely used in networking for the purpose of controlling the traffic entering or exiting a network node. Furthermore, it is indicated how to integrate the user perspective metrics with the optimal algorithms for system performance metrics developed earlier by the authors. Simulation results illustrate the effectiveness of the proposed framework.