... >Also, a D400 (w/ grip) would approach a D4 in frame rate, >something that neither the D600 or D800 does. So, would Nikon >offer only one camera that shoots at a high frame rate and >price it at $6,000?
The part I don't get is the processing throughput constraint, judging from EXPEED3 capability on other cameras such as the 24mp D600 that supports up to only 5.5fps. Only the 16mp D4 can do 10fps and of course the D800 is limited to 4fps.
Is that the delay then, processing power and we need EXPEED4 for the D400? Or is a 24mp sensor on DX inherently able to do faster, such as 8fps with grip, where as 24mp on FX Nikon can only get 5.5fps out of it?