Providing Quality of Service (QoS) to inelastic data transmissions in a cost-efficient, highly scalable, and realistic fashion in IP networks remains a challenging research issue. In [14], a new approach for a basic, domain-oriented, reactive QoS system based on so-called Load Control Gateways has been proposed and experimentally evaluated. These load control gateways base their load/admission control decisions on observations of simple, binary marking algorithms executed at internal nodes, which allows the gateways to infer knowledge about the load on each path to peer load control gateways. The original load control system proposal utilizes rather simple, conservative admission control decision criteria. In this paper, we focus on methods to improve the admission control decision by using probability theoretical insights in order to better estimate the load situation of a bottleneck on a given path. This is achieved by making assumptions on the probability distribution of the load s...