GW fanboy here. IIRC, additional detectors provide better ability to locate the GW source so that other telescopes can also capture an event. They also improv

GW fanboy here. IIRC, additional detectors provide better ability to locate the GW source so that other telescopes can also capture an event. They also improve polarization measurements. The number of detectors doesn't determine the false positive rate which is just a user selected point on a receiver operating characteristic curve. In general, we get more pay off from improving detect sensitivity than from having more detectors (that's why GEO 600 was more useful for the tech it developed rather than its most recent observations).