I hesitated in replying because I don;t yet have my D600 at hand but I did look into this issue last year with both my D300s and D5100.
The work around you described was 'doing the rounds' online but I seem to recall it was debunked. I tried to locate the source of that but couldn't and besides now we're talking about a different body.
Should it not be actually visible with a small prime for example to set the camera up and look from the front to see if the aperture blades do in fact move with exposure compensation?
Do you have a link to the tutorial you mention? Is it actually with the D600?