>So the D4 is really that much better in low light when it >comes to focusing ??
I find the D4's autofocus to be pretty amazing. My only gripe with my D3 was low light autofocus. Not that it was terrible, but I did miss shots with it when light levels got low. I skipped the D3S since it had the same autofocus performance. My D4 will focus if I have enough light to compose.