I was checking out some new birding locations yesterday and trying out my new toy, i.e., D300. Here's a highly cropped flight shot with a 700-300 on D300. Sharpened and enhanced colors a bit.
Comparing with my S5, D300 does seem to be able to do a better job on focusing and tracking. Then again, I wouldn't expect anything less
If it looks like the bird is cut out from a cardboard...well, it's just the way it is