I have a Kata 3n1-20 and i loved it. It was the perfect bag while i was tripping around Australia. Coincidentally i have one for sale. :)
http://www.texasphotoforum.com/forum...highlight=kata
I carried a NIkon D300 + grip with a 17-55 attached, an 85mm f/1.4, a nikon SB800, 2 pocket wizards, and some extra AA batteries. And i even had the extra compartment up top free and open. Also used a tripod connected to the outside as well.
one thing i think you might have problems with is the 55-250. I'm not sure how big it is.
I have a Nikon 70-200 VRII now and it does not fit in the bag any where. But its massive.