I was convinced I had to have a solid tripod to get great shots with my D800e until I went shooting birds with David Hemmings. After making some settings changes (all related to AF), I was able to get great shots while hand holding with a 200-400mm zoom. I also started using a BushHawk with the lens to get even better shots. I will still use a tripod when shooting landscapes and animals/birds who are not moving much, but I now feel free to shoot without one.
I keep the ISO as low as I can for good details and low noise...usually under 1000 for birds and 100 for landscapes, but I also focus on the shutter speed. I generally use 1/3FL for hand held shooting even with the BushHawk.