I’m running three Dell PowerEdge R710s (not clustered), 128GB RAM each, dual Xeons, with Proxmox. Across the trio I host ~10-20 LXC containers and 8-15 VMs. Per box I see ~350W peak, ~250W average, and ~160W idle (single 570W PSU, mostly SSDs). Lab‑wide that’s roughly ~1.05kW peak, ~750W average, and ~480W idle... Tweaks like L‑series CPUs, a single PSU, and BIOS power‑save MIGHT shave ~20–40W per node (not sure I'd want to do that though)... but my systems will never sip like your 50W SuperMicros!
So yeah... I definitely would like to explore these options at some point either myself or if someone else beats me to it.