I confirm it works on both the older 107C Element drives from 2015 and the current 2017 model Element which is the 25A3. Please note I have tested this on the rounded My Books and confirm it works, but I have not tested the rectangular My Books. If you removed the drive and put it into your computer it would not be recognized.
Obviously, the external enclosure is needed for a 4TB MBR partition. The USB interface still contains the emulation needed for XP, even though WD now defaults to a GPT partition. I then connect it to my XP machine and I can read and write to the the full 4TB partition, no extra software needed. I select XP Compatible in the format options and it creates a single 4TB MBR partition. To make the 4TB drive XP compatible, I connect it to a Windows 7 machine and format with the WD utility. But the current My Book and Elements (model 25A3) have a GPT partition and need to be reformatted to work with XP. The older 4TB My Book and Elements (model 107C) used to come with a MBR partition. I am an XP user and can say that the 4TB My Book and Element drives are still working with XP.
