D5k - Frame rate was 4 fps, but it went on for 50 jpegs or 11 raw (actual usage on my old D5k. dunno what the specs actually say).
D7k does 6 fps, but can only capture about 14 jpegs or 9 raw (as seen on my D7k).
No idea why the jpg to raw ratio is different for the two cameras.
The 50 jpeg shots go a long way when trying to shoot BIF on a lens which focusses as leisurely as the 150-500.
I dun know if both raw files are exactly using the same technology? or perhaps different files size and resolution?