回复：前几天有网友说，D700之后是D800，而且D800是24m像素

the main advantage of full frame is at its sensor size.  bigger sensor NORMALLY means better light sensitivity and better image quality.  with the available technology, both hardware and software, a bigger sensor should always be better.  to me, the most obvious benefit of having bigger sensor is the way better low light sensitivity of the full frame.  of course, you can have better on camera software to tweak the noise issue, but it normally sacrifice resolution and image quality in exchange of reducing noise.  d7000 is probably the best aps-c camera with great software that reduces noise.  i kind of think 24mp is the maximum resolution you can get for full frame before hitting the noise issue, with available hardware and software these days.  may be in the futrue things change.  the chromatic abberation should not be a real big deal because lens these days have special glass that will reduce CA, and on camera software will just automatically detects it and remove it from the image before even showing it on screen.  you can always PS it afterward too.  if the CA is so difficult that you can not get rid of it with both hardware and software, then i think you will get it with the aps-c camera too. 

i dont think the 24mp d800 will be much better than the d700, at least at its speed and low light image, unless it has much better software.  supposedly, the 24mp sensor should have more noise issue than the 12mp of the d700 sensor.  of course, if the software on d800 is so good that it produces a low noise image rivaling that of the d700 at low light, or the d800 sensor is a significant upgrade from the d700 sensor, then that is a different case.