I want to bump this one.
Equipment for the bag would be 2 eos-1d's, 16-35, 24-70, 70-200 2.8, and
15" MBP. Would I have room for this stuff in a d550?
I am not bumping, I just came back from purchasing one today (the D650) and it does in fact hold the 17" MBP perfectly. I plan on loading it with the usual journalist gear and a Marantz recorder and maybe a few pieces of etc equipment.
I had to choose between that one or the D550 which is widely available and getting a smaller book. Once I read the dimensions of the bags, and compared them to what Apple says about the MBP's size, I felt safe knowing that the D650 held the 17" MBP and the D550 was made for the 15". Before the SR's went "digital" the bags only held the 12" (because it was a perfect for PJs) and the 15" books.
You will be fine with the D550 since even the D400 can hold what you are asking reasonably. The biggest difference will be the slightly longer width to hold the 15" in the D550, and the added width and depth in the D650 to hold the D650.
After looking at them for about two years and destroying my SR400, they are all the same save for the laptop adjustments.