There are many grades and variations of nylon. I have a small Gregory made with Sil Nylon, which is thin and light, but not as durable as the heavier nylons. Most of the major backpack manufacturers will use a good grade of nylon.

One thing I will recommend for your area, as I have done some time in the Southwest of Australia, a good durable nylon is a good thing. Everything there seems to want to tear, poke or abrade your gear. I don't think that something like Sil Nylon will last long there.

The design of the bag you linked to seems OK, but with some off brands what you will find is defects in the manufacturing. Sometimes that includes poor materials, like inferior plastic buckles, and sewing that starts to come apart right away. If you do go with something like that, make sure they have a good return policy.