VK4EBP reported that he has carried out successful tests over a 10km NLOS (non line of sight) path using infra red.
See Australian Optical DX https://groups.yahoo.com/neo/groups/Optical_DX/info .
One of my aims for 2015, assuming I am fit enough, is more NLOS tests including IR over greater ranges. To maximise my chances I shall probably use QRSS3 again rather than rely on aural reception. My previous tests, using clear air scatter, was over a 8.5km distance. Much further should be possible.