The list you have can surely be filled with either camera, the question is, are they features you will use. I have gone from a D50 to D200, then last year to D700/D300s combo. The bracketing is something that I thought I would use more than I do. Only twice in the last year have I set the bracketing mode and once it took five minutes to figure out what was wrong with the camera the next time I used it . On the other hand, the higher ISO, faster focus speed and frame rate are things that I use daily. My advise... use the D40 with the new lens for a while, if in that time you have problems that a new camera will fix you'll have your answer.
Will shoot for fame...fun...food... a heck I'll shoot anytime anywhere.