I am shooting with a D3s as my main body, and I have a D300. I would like to replace the D300 for a better camera body for travel and to use as a second body. I am looking for some suggestions as to what to purchase. I read that the D400 may come out this year replacing the D300. Is it worth waiting for, or would a D600 work as a lighter body for travel and a 2nd camera. I think the D800 would be over kill as a second body.