Bought the Circle Reverse Osmosis system two weeks ago.  Considered hiring a plumber and thought I'd give it a shot myself once the weekend came.  I could not have been more pleased with the simplicity of installing this system.  Within about an hour we were already filling and flushing.  We are so happy with the end result, it looks great, tastes great, and works flawlessly.  I would highly recommend this to anyone looking for an RO system.