I just received my Nodal Ninja 3 MkII this morning. At lunch I went out to set it up. I used it on a Canon 40D with the 17-55 mm IS USM lens. I tested for parallax using a sign post approx 3 ft from the tripod and the edge of a building approx 1/3 of a mile away. With the lens set at 17mm there was no parallax with the upper rail assembly set as far back as it would go. At 20mm there was some barely perceptible parallax at that setting.
So this combination of body and lens just fits the Nodal Ninja 3. I would recommend anybody using this combination to buy the Nodal Ninja 5. I wish I had done so. I am contemplating upgrading. Since this is the longest lens I anticipate using I may not go to the trouble.