I am a no longer pro photographer and just do it because. I have been using a caselogic slr backpack for several months now and know the good and the bad of these setups. The best thing about them is that they dont scream here is three grand woth of camera stuff like the standard bags do. This means alot these days.
Ok the Lowepro is water resistant, a little moreso than the caselogic which has no flapage (is that a word, well it is now) to protect seams. It is better laid out than the caselogic that runs about the same price, but…. the case logic is more solid in that it has a tube compartment that your slr with a long lens fits into like a holster from the top of the backpack, while the Lowerpro just has the badded velcro dividers. So there is some good and bad, but it just depends on what you think you will utilize most. The very bright side is either way you go you will have quality that wont let you down. One note there is not enough room for all your stuff like the lens hoods, but you can get creative and minimalistic and get it done right. Things will fit inside your lens hoods etc.
These packs are the way to go for stealth, comfort, and protection. Also think of your family when you are in another country. Unwanted attention can be problematic.
Good luck to you and happy snapping.
polyester construction
All weather cover protects contents from the elements
Removable padded inserts allows for customization
Hide away tripod mount with foldout holder, cam lock buckles and straps
Airline friendly designed to fit on most airlines
Fits a dslr with attached lens (up to 70-200mm f2.8 plus 2-3 lensesflash and accessories; tripod or monopod; personal items