1D2n maybe, but not the 1D2. With the 2n you'll gain better build and better AF, but lose some screen size and menu convenience (not as much as you would with the 1D2 though). Honestly, after getting my 1D3, holding my 40D (even with the grip) just doesn't feel as good. The viewfinder makes a bigger difference than I ever would have thought too. You mentioned landscapes so your 17-40 would be a little wider which is a plus. You'll also lose some on the long side of your 70-200 (not sure if that matters to you or not).
ISO performance should be similar and you'll no longer have the pop-up flash in a pinch (I have never used mine since owning my 40D so if you're like me that really doesn't matter). I never use my 40D without the battery grip but now that I have the 1D3 I have given serious consideration to de-gripping the 40D and getting a 28 f1.8 to use as an around the house snap-shooter. If it were me in your shoes I would just keep the 40D and get another lens or save up until I could make the jump to a 1D3. That move will really make a noticeable difference across the board.