The lab is now running Ubuntu 16.04.

One new thing is that I had expected PXE booting to 'just work', but it's been a bit hit-and-miss. I have no clear understanding why, but I might be able to find out by comparing UEFI/BIOS settings on the machines to find out what the differences are between machines that CAN PXE boot and those that CAN'T.

The machines have two distinct motherboards (ASUS H81I-plus and ASUS H97I-plus), and there are slight differences between the models' UEFI/BIOS.

Machines that can PXE boot:
Saga (H81I+)
Salander (H97I+)
Smilla (H81I+)
Sherlock (H81I+)
Cadfael (H97I+)
Rumpole (H81I+)
Poirot (H81I+)
Morse (H97I+)
Marple (H97I+)

NOTE: F8 should boot the machines to a boot menu that contains UEFI network booting.