Mick

I think you will see that same "tonal" quality out of the 1D IV you see out of your 1Ds III.

The real benefit of the 7D over the 1D IV is the crop factor and if you stick with the 7D it will keep $3,400 in your pocket to buy something else.

The 1D IV will do every other thing you have asked for and more. Like I said before, the AF system was worth the upgrade to me. But I am an amateur, if I miss the shot I still eat. But I take my hobbies serious, if I spend days planning a trip, hours getting to a location and hours waiting for a pic I want the highest chance I can get to make sure I get the shot. The 1D IV will do that. But if I was still using my 50D, I would be just as happy with my hobby. Is it worth the upgrade is a personal question that each of us amateurs have to ask ourselves.

You could wait several months for the 1D X. It might serve your needs even better.

Good Luck with what you decide.