> • try alongside other traffic on the endpoints, and note that TCP streams can't find their achievable rates (or split the available bandwidth amongst themselves) without hitting the packet-dropping pressure that also affects UDP. So perhaps try with 1, 2, or more TCP streams doing a max-speed copy at the same time.

I agree. Having (or not) other traffic on the network will impact UDP throughput dramatically. As one who does VoIP QoS will soon find out.