It's fully utilizing the cores (minus one for some reason... maybe the scheduler thread is included in the thread limit?) so I can't see a huge gain other than running it on bare metal.
The opteron cores are not as efficient per ghz as the haswells. The only advantage is that you have physical cores without any hyperthreading. I'll try and compile the miner on 12.04 to run it on bare metal and see what/if any advantages are seen vs running it kvm with cpu passthrough.
The server is about $3300, so it's not exactly cost effective. Just fun to see.
edit: just noticed the instructions to install it on 12.04, derp.
http://i.imgur.com/iH7vs4r.png