My experience (almost) mirrors yours. I had money stashed for almost two years, waiting on the D4. When it finally appeared, I concluded that it really wasn’t what I was looking for. I needed a low-light compliment to the D700, mainly for shooting rock-n-roll in poorly-lit venues. I found a decent deal on Ebay with 5000 clicks on it, and I was immediately bowled over with the performance. Better auto-focus, three times the buffer, and (I noticed), substantially better IQ. It has afforded me the opportunity to get stuff I wouldn’t have gotten otherwise. And I saved $2200. Couldn’t be happier.