First impression: It is much bigger than the SB-800. Didn’t really seem any heavier, but definitely takes up more space. This is a consideration for a couple of reasons. One, cubic inches matter when on the road. Not so much on a single flash basis, but if you are packing half a dozen SB-900s, you could probably cram seven SB-800′s in the same space.
Also, the head is a totally new design and size. This means that your current light modifiers may or may not fit the SB-900, depending on their size and/or mounting flexibility.
