I think either bag would probably fit what you've listed, but it may not fit in how you'd like and probably wouldn't have space for anything else. Well ... there'd be a bit of space, but things would most likely start to stack up strangly.
I think if you removed the (vertical) dividers altogether, lay the 580ex on the bottom of the bag and then put the 5D2s on edge with their lenses facing each other, resting on the 580 it could work. There may be other ways too - I can play with it a bit if I get the time this afternoon.
Your Ipad could go in the bag, between the back of the bag and the back of the removable padded liner.