I don't know if either version will produce a better landscape than the D700, no one does. At the moment the whole issue is hypothosis and will remain that way even after the first D800/E hits the users here. I have almost made my decision to not upgrade my D700 even though it may result in the D800 being an almost joint DX and FX camera. This is an important factor as I photograph both wildlife and landscapes.
My guess is that the D800 or D800E would provide me with much more than I have now, that is the ability to print stunning landscapes up to enormous sizes. I only produce 20 x 16 or normally 16 x 12inch prints. I don't need bigger images and guess I never will. The question is this, at the same viewing distances will I tell the difference between the D700 and D800/E. I don't know. I sell my prints and those I've sold to are pleased to have them on their walls.
So perhaps I've answered my own dilema, perhaps not. All I can say is the D700 is no lightweight as you already know, it is supremely capable of producing printed images of which anyone will be proud.
I guess the answer you need will come in time and if it's negative then the D700 will hopefully still be around and the diffrence in cost would be a major contribution towards really good glass.