Whenever I get my hands on a new higher pixel density camera, photographing the moon has been I try. I received my 7D last week, but only yesterday did I have a chance to photograph the moon. Its a little too full for my taste, but still the detail is there.
These crops show that even with a 1.4x TC the lens is able to deliver enough resolution for the 7D's high pixel density sensor.
Technical Specs: Canon 7D, 800 f/5.6 IS + 1.4x TC, f/11, 1/200s, ISO 400.