Recently, wireless sensor and actor networks (WSANs) technology has been also applied for monitoring critical infrastructure protection (CIP). These new applications make more demanding requirements of WSANs and therefore it is necessary to develop algorithms that can manage the communications and route the information from each sensor node to the sink nodes while providing quality-of-service (QoS) requirements. In order to assess the current state of WSANs in terms of performance and QoS support, this article empirically studies the performance of a network with different workloads in terms of reliability, delay and queue occupation with common network topologies. The results reveal the intrinsic lack of reliability and low throughput that this technology currently exhibits, the importance of matching network level capabilities to data link layer capabilities and different behaviour of a PQS in terms of reliability and delay depending on the congestion of the network.