I also sold my Nikon 24-70 f2.8 because of the weight as well and bought a 24-120 f4. I truly can say I have not been disappointed. Without doing some major pixel peeping I can see no quality change. I really love the 24-120 because of extra length. I hope the same is true for my 70-200 f4. Should be here today.
Additional Info: I was shooting a D700, but now have D600.