It's an interesting decision - WD is expanding their low-power 3.5" hard drive offerings with a second line at the same time Seagate exists the "green" market, claiming low-power drives aren't really all that beneficial or quite frankly, special.
Best in class power consumption; Strongest sequential read and write performance; Suited perfectly for SOHO NAS environments
Best in class power consumption; Strongest sequential read and write performance; Suited perfectly for SOHO NAS environments; Weaker random I/O performance seen in our mixed workloads