Quick word of caution on those roof bags - I had one that I used for a while because I didn't want to drop the money on a quality cargo box.

I'm not sure what the weather is like where you're from or where you plan on going, but the straps on my bag didn't last very long and broke the last time I tried to tighten them. I'm thinking it was a combination of the rain/humidity and sun down here in FL caused them to rot/become brittle. Could also have been the materials used by the manufacturer (don't recall what brand it was and it's long gone).

Just something to keep in mind since that's not a concern with a cargo box and the clamps used to mount it to the crossbars.