The F difference is still pretty huge to me. Just for random reflexion, DoF at 5m is 1.7m at f1,4 vs 3.8 at f2.8. And that's just the math, the feeling is even stronger when I look at my pictures. Same for ISO. Yeah we can push it but should we?
To extend what alexander said the use, the feeling when shooting and the "creativity by self limitation" are also to take into account.
So +1 to the original post of Dylan, If you don't need the cash don't sell.
24-70+70-200 for efficiency, 35+85 for pleasure.