Originally Posted by MikeFold

I remember "back in the day" (a previous chapter in my Walter Mitty Life) when I was one of the first to acquire a New Nikon F3 HP for my photo business. Because I owned a One Hour Photo Lab and a Custom Photo Lab, as well as being a commercial photographer that specialized in product shots and model portfolios, it was expected of me to be a "Cut Above" the 'average' so called photographer. The Top of the line Cameras and most recognizable (and unaffordable) were always cutting edge Nikons with the legendary Nikkor Lenses. So, when a potential customer came to my office to contract a job, the Nikons were always in full view (as well as my calling card, a Mamiya RZ67 with all the bells and whistles).
My point is: If you are going to be the best, you need to use the best. (there are exceptions, I am speaking in general terms here). Back in my day, Nikon was the best. If JFK feels he can take better pictures with quicker response times, and wants the best model he is comfortable with, and takes his business seriously, the Nikon D4 is worth every penny he pays for it.
Comparisons are a waste of time because half the battle is being comfortable with your equipment, whether you are golfing, racing, or taking pictures of people.
Have fun in Phoenix JFK.