A very interesting series, testing the Feisol 3442 with various leg extensions at 200 and 280mm using the 70-200VR and D200.

These images might suggest that these legs are actually more stable with all 4 sections extended than with the 4th section retracted. That leads to the very interesting question: Is the 3 section 3342 more or less stable than the 3442? That would make for an interesting test! Your guess is as good as mine.

Keep in mind that these are controlled indoor tests without wind. In the wild windy real world, I would certainly shoot as low as possible, regardless of whatever these tests suggest.