I appreciate the use of ballast to stabilize something. The D3 with 70-200 or 80-400 is rock steady.
I wanted a D3100 so badly just for trips and hikes. But, I got rid of it just because I could not hold it + a little DX lens steady enough.
I am an EVENT Photographer and I often hand hold a camera for up to 8 hours during a day while taking thousands of pictures. One HillClimb started at 7 AM and finished close to 8 PM. See how long you can hold and empty hand out in front of you.
I find the D7000 + 28-300 lens just the right size, weight, and grip for me without adding the extra battery pack.