I would love to see some pics of your trotteur. You're right about the camera taking up so much space...even though it's small, my Treo and sunglasses will take up space too.I would get the Trotteur cuz it can carry more for your trip. You can carry a camera, cell, makeup, sunnies...etc all in the trotteur while the camera would already occupy 1/2 the pochette accessoire, so the sunnies would not fit in at all.
I have some pix if you want to see.