Well after a lot of thinking and more experimenting, I have decided to sell my Sigma 18-35 today to the buyer for $600cdn (which gets me all my money back that I paid for it last summer) and using $250 of that $600 to get me a new 35mm 1.8G and the remaining will get me to break even on the difference on what I paid for the Nikon 17-55 a few weeks ago. Because of that, I can afford the 24-70.
The Sigma is just not a useful range for my uses (got this feel every time I put that lens on the camera) and the few times that I did use it, I only used it at 35mm (hence why I am buying the 35mm 1.8G). The Nikon 17-55 is much more useful for my needs because of the range. I should have sold the Sigma many months ago but it was the gear head syndrome that "Falsely" convinced me to keep it because it fitted my needs but it wasn't a good fit at all.
Since I will pretty much be trading my Sigma 18-35 for the Nikon 17-55 and 35 1.8G, the latter is a much better fit for my needs than the first.
What can the 24-70 do that my current kit can't? the 56-69mm focal range. No seriously though, I see the 24-70 as the mini 70-200. Perhaps it will pair on the second body better than the 17-55 would, and on the level of how well my 100-400 pairs with my 70-200.
. Still don't regret buying this model (it's worth it for the touch to focus and size alone) but I wish it had MFA.