Comparing the 3 head to head:

In excellent lighting the F707 takes the best photos. It also would get the edge for the ability to take flash shots in NO lighting (has laser illuminator). The 400 ISO mode is fairly useable.

The S602 takes excellent shots - good white balance and exposure - over a wide range of lighting conditions. It is the best of these 3 for LOW lighting shots - where there is low ambient light but you don't want to use flash or a time exposure - provided you can handle the 1M limitation for its 800 and 1600 IS modes. I was pleasantly surprised to find even in ISO 1600 it is not grainy and quite useable.

The autofocus in the D7i is infinitely better than in the D7, and it looks like they may have improved battery life a bit too. The evf is the same as in the D7, which means worse than in the F707 and S602. The D7i has nice retro knobs for much of its human interface. But I find even in daylight the majority of the shots are way too pink, under exposed, and not sharp. I think the S602 actually takers a better shot under most circumstances than the D7i! The higher ISO modes (400 and 800) are so grainy as to be virtually unuseable.

The lack of memory for picture numbering in the S602 is a major design flaw. Q to anyone out there using it with a digital wallet or variation there upon - can one safely do this with an S602????