Will a new D800/600/D4 improve my work?

I do not think I am missing shoots with my current equipment... Will the new line up enable me capture more shoots. Am I limited by my D700 & D300. If I buy a D800 a D4 will I see a differance or will new and improved equipment enable to get more or better results. I read the reviews and see all the fancy numbers but my question to those who have upgraded is what results are they seeing and how much better is their work???  I was planning on some new equipment because it is nice to own the newest equipment. Unfortunately the recent storm that hit Long Island has left me financially devastated and need to reconsider what is important.