Wireless Sensor and Actuator Networks (WSAN) and permanent connections to the Internet converge to be an emerging and promising field: Machine-To-Machine (M2M) services. To take advantages of this new field, hardware and software infrastructure compliance must be verified. Services expected by M2M alter the organization of WSAN. The software design in this area can be divided into two main categories: a centralized approach (Orchestration) where a monolithic application collects data and sends orders, and a distributed approach (Choreography) in which nodes offer and use services in a collaborative way. In this paper, we study the impact of these two architectures over WSAN. First, a mathematical analysis shows the improvement offered by choreography, thanks to the use of shorter paths between nodes. Then, an application experiments these two architectural designs to measure the impact on a real testbed. Both the theoretical mathematical analysis and the real platform experiment gives better results for the Choreography in terms of network reliability and path length. Our work quantifies the benefits obtained and provides histograms and numerical results.