The seven-station test-bed for the ARIANNA ultra-high energy (UHE) neutrino telescope, the Hexagonal Radio Array (HRA), was completed during the 2014-2015 Antarctic summer season. In the more than four years since, the ARIANNA pilot array has demonstrated remarkable resilience and stability, surviving multiple Antarctic winters while operating with a typical 90\% uptime during the summer months, while the ARIANNA data acquisition system has proven to be capable and cost/power efficient. A combined analysis of 4.5 years of data from the pilot array will be presented. The neutrino search yielded no candidate events, with a signal efficiency of 79%, providing an updated limit for the diffuse UHE neutrino flux of $E^2\Phi=1.7\times10^{-6}$ $GeV cm^{-2}s^{-1}sr^{-1}$ at a neutrino energy of $10^{18}$ eV. Data from the operation of the ARIANNA pilot array will inform the design of the next generation of radio neutrino detectors, which will be capable of probing all but the most pessimistic models of the GZK neutrino flux. It will also be shown that such detectors will have an important role to play in the multi-messenger detection of point sources.