Built this same design to run a single bucket with additional reservoir capacity. Just wrapping up my first grow with this config (maybe my 15th dwc grow overall) and here are my personal findings:
Pros:
Safe, water flow is relative to water level so overflow/draining is not a worry
Simple...
For anyone who needs a quick laugh ...
My roots weren't looking as nice as they usually do on 2 plants I started on DWC last week. Figured out I had plugged my air pump into the light timer power strip. Live and learn.