I believe the Kata Sensitivity is the ultimate for checking in bags if you carry a laptop. Everything is easily accessible, and the laptop compartment fits most 12" laptops, and can store your camera gear safely with ample protection. When I hit the ground and check in, I change to a good shoulder bag from Neunpro.
i used to carry a Crumpler 7 Mil for a DSLRw/ grip with 2-3 lens, and I usually had problem with the weight on my shoulder after 2 days.
Recently, on my 3 weeks travel trip.....I was using a LoewePro Slingshot200...and simply love it!
I can swing it from the back to the front in less than a second, and swop lens easily with the zip opened.
Dont know how to explain, but you should go over to some shop and try it out.
Dont worry too much about your huge backpack. Most of the time it will be in the hotel instead of on your back. Just bring whatever camera bag you use in sg. You should have no problem with it.
The only time i had my backpack with me is when i'm on the move (taking a train/bus to another location and on my way to the hotel).
Is the gorillapod very useful? I am considering if It's a worthy investment for travels too.
Also, I liked to know, those carrying backpack around, wouldnt it be very troublesome to load/unload your camera/lenses as you move around. I have since switched to carrying a backpack to throw my misc stuff and a 190AW for my photography equips