Monitor resets with OWC Thunderbolt 2 Dock?
January 22, 2016: I had similar problem (intermittent monitor and hard disk disconnects) and called the OWC HelpDesk.  The OWC technician said that problem was with the Mac Thunderbolt driver, not the Dock, and the solution is to reset PRAM/NVRAM: https://support.apple.com/en-us/HT204063
Since PRAM/NVRAM reset, the intermittent screen and disk resets have stopped.  I am keeping fingers crossed.

January 30, 2016: The monitor/disk disconnects have restarted :-(

February 9, 2016: Has worked flawlessly for past 10 days, following another NVRAM reset.  I wish I could understand the problem a little better, what causes it in the first place and why it goes away after NVRAM reset?