It is not so that the Drive Manager would be completely useless, but in the system log (console) he produces every few seconds an error message ("WDDriveManagerStatusMenu [35498] *** attempt to pop an unknown autorelease pool (0x1029600)") - the but can not be healthy! He is also stuck when setting up at me once, and the second time was displayed after setting nor the old RAID level.
Something in my opinion is to a nerve in a product that is to be used as a backup device - the essence of a backup device is however that there are still 100% working well after a few years, and not sickly already with the NOW current systems - moreover, with 5-year warranty.
WD can not ask seriously that I an outdated operating system install on my MacBook to be able to use only a properly now newly purchased device.
Too bad for WD.