So, I've just replaced my Lowepro Compurover AW with a much more compact Kata DPS DR-467. It's a backpack with a laptop section, a day section, and the camera section at the bottom. Build quality is outstanding - it feels incredibly well built, and protective.
Weight & size is excellent - sure the bottom could be a bit more spacious, but I can still fit in my 40D with 24-70 (+ reversed hood) on, my Sigma 10-20 (+ reversed hood), Sigma 30mm (+ reversed hood), and just about my 70-200 f/4 (+ hood reversed). On top of that, there's still a bit of space for a couple of batteries and memory cards. It's a bit of a squeeze to get the 70-200 f/4 in - it's the very longest lens you can fit in the bottom section.
In the top section, there's plenty of space for other stuff - it's the same size, or larger than the top section in the Lowepro Orion Trekker. On the outside of the bag are three zipper pockets for odds and ends. There's also a slot to feed out your headphone wire, should you want to keep your music player in your bag.
As I said, the weight is excellent - the bag weighs less than 1.5kg (approx 3lb) empty, but even fully loaded, the padding is so well placed, that I find it far less tiring wearing this bag, than the Compurover it replaces.
You also get a free waterproof cover (think detachable Lowepro AW cover), and 5 year warranty, extended to a lifetime warranty on registration on the kata website.
My one quibble with the bag, is that you need to be careful with it - like the Tamrac expedition bags, it's possible to get into the camera compartment with it on your back, so if carrying on public transport, beware.
Would I recommend this bag? Absolutely! Sizewise it's very close to a Lowepro Orion Trekker, but in terms of capacity, and comfort, it feels closer to a Lowepro Compurover AW - no mean feat! (photos to follow)