Why would any consumer or even a small business want or need a 6TB hard drive? Supersized hard drives take longer to back-up, restore, wipe, and maintain (i.e., defrag, scandisk, etc.). And even if I had enough photos, music, videos, and other files to file a 6TB hard drive, I wouldn’t want all that important data on one disk at the risk of a hard drive failure. Yes, I realize that these issues can be mitigated by partitioning the hard drive, but this is far beyond the expertise of most consumers and I have had entire hard drives fail notwithstanding partitions. Seems to me that the better approach is to have multiple smaller hard drives — one for the OS and programs, one for data and media files, and one for backing up the other two.
I would also use Dropbox as another backup, in case a fire destroys all of your hard drives.