As well as building this brilliant proper portable cloud, Karanbir also helped me to choose parts for my rather cheaper non-portable caseless alternative:

https://rwmj.wordpress.com/2014/04/28/caseless-virtualizatio...

There was another article on creating a portable cloud setup with Intel NUCs at Joyent blog few months back:

https://www.joyent.com/blog/spin-up-a-docker-dev-test-enviro...

I wonder what the cost difference would be between this setup and the original article box?

I thought this was why things like the big end ThinkPad W-series exists?

I still run 3-4 VMs at the same time on my ancient X201 on Hyper-V.

what are the advantages of this over just having a machine with many VMs?

If you are messing with virtualization setups, hypervisors and low level os/kernel things you often can't (or at least don't want to for speed, stability etc) be in a virtualized environment as your base layer.

The configuration outside of VMs (e.g. routing) is slightly different. Apart from the obvious fact that - depending on the the hardware used - you can get more computing power than from one machine.