Yes, as others stated the zippers sometimes catch the fabric (just cut it away if you don't need the zipper to be covered in case it rains), and yes its lower density material (600 vs 1200 in military stores), but they easily cost another 30 to 40$ more.

I looked at the ones in the PX, but since i don't need the thicker material and definitely not tye higher price, so this will be perfect to use as daily backpack if you don't jump out of C130s..