For Back pack quite cumbersoem when you wan to change lens etc..Usually for me i (my setup 300D, 70-200L + 17-40L + 420 Ex Extra batt, Batt grip, Data storage disk...) I put every thing in a Nova 4 aw to hand carry on flight dun ever put it in the luggauge..esp china...they throw it ard.. For touring ard and in singapore i bought a medium size pouch put the flash, accesories etc then a Lowepro TLZ1 for my cam body wif grip+wide angle.. attach my zoom len in a len bag to the pouch and sling my tripod . This help me distribute the weight abit more evenly..Lolx My wife say i going for war..but it is easier to change lens.. and get ur gear rather than a backpack. Bad experience with sling back cos gone for 20day holiday in china come back sore shoulder and need to see sinseh for rubbing...But Again it ur choice lolx..and do u need to change lens frequently..