I know. It's not the sling type but double shoulder strap like normal backpack. However, because of the material; it's more rigid and if no proper meshing at the back for ventilation, the heat generated would be more. Thus the uncomfortable use.
But again like explain before, you'll have to test it out to see whether or not it suits you.
One point to note though, if you don't take care of your dry bags properly you might risk the "skin" peeling off especially at the top where you need to fold 3 times to clip it for it to be waterproof.
@hao
You can try this. Start "packing" without the bag yet, i.e. take out all the things you wanted to bring. So roughly you would know how big the "pile" is as everyone's definition of packing for 1 week is different.
So once you have a gauge on what you wanted to bring and how big is the pile, then after seeing the real backpacks; you would have an idea whether or not it would fit.

The price however I'm not very sure.