Comment 3 for bug 1687333

It is straightforward to use zsync to keep the daily iso files up to date. There are links at http://iso.qa.ubuntu.com/

This way you need only download the differences between yesterday's and today's iso files. And the iso files are checked automatically by zsync.

Then you can use the daily iso files to install systems into external drives. A 64-bit Ubuntu iso file makes a DVD/USB drive that boots in BIOS and UEFI mode. The installed system will boot in the mode, that was running when you installed it.

There is a problem is with the bootloader. Installing the bootloader is flexible (but somewhat risky) in BIOS mode. In UEFI mode the bootloader will go to the internal drive['s EFI partition] whatever you specify unless you disconnect the internal drive.

To make the computer available for safe testing, I would recommend to disconnect (unplug) the internal drive and have the production system in an external box (for example an SSD in a box with USB3 or eSATA connection).