myone, this is exactly the direction I was thinking of going too. What brand of insert do you use. I was thinking either the f-stop medium or the crumpler Haven Lg
I am using the Mountain Smith Kit Cube http://www.mountainsmith.com/products.asp?productId=290&categoryId=13&subCategoryId=29&subCategory2Id=0
It has a storm cover with drawstring, perfect for double protection from water.
As noted by a forum member earlier, the Guru F-Stop is another great choice but you are paying a lot more money for a heavier 2.6 lb backpack. When traveling, the lighter the better.http://fstopgear.com/en/guru
I am using the Northface Angstrom 30. This little 33 liter pack has a lot of storage. It is built with very lightweight material, weight 1+ lb and has an internal pouch for TNF water bladder/laptop/ipad, etc. The materials are very durable, sealed zipper for complete water proof. Also the backpack itself is waterproof, and comes with a water resistant jacket in case you need it. My last trip to Asia ran into many days with heavy downpour. I was on waterproof jacket without umbrellas and the backpack was exposed to heavy rain all the time. I did not even have to use the included water proof jacked that is tucked into the side water bottle pouch. http://www.thenorthface.com/catalog/sc-gear/equipment-technical-packs/angstrom-30_2.html?from=subCat&variationId=JK3&cm_mmc=Google-_-ProductListingAds-_-Product_Terms-_-The%20North%20Face%20Angstrom%2030%20Pack%20Tnf%20Black%20OS
The backpack is also built with breathable back support material, chest strap to load even the weight, as well as waist straps. One neat thing is that the waist strap can be tucked/hidden inside the back support panel if not needed.
The Mountain Smith insert is wide enough that I can just rest my 40D + 24-70 with hood attached on top of it. The dividers are strong enough to let the camera+lens rest on top of it side way with a good amount of "collapse" to secure it from moving around.
It worked well for my last trip and will be using the pack and insert again this year for my 3 weeks in Asia. This time, I will also bring my Crumpler 6 Million Dollar bag for more city friendly.