The Snippers in Valkrum Dunes DO NOT aggro. I know this for a fact. I was standing infront of about 3 of them and just left my PlayStation 2. Meanwhile i did my homework, came back and not a single damage tooken. (Note) I was on my level 16 Black Mage. So you know if it was to attack me i would have been dead.
These guys definitely do link in the Dangruf Wadi. I am positive that they do not link the Valkurm Dunes, though. As for aggro, I honestly have never seen one aggro, but I don't doubt that they can in certain areas, or if the target is low on Hit Points.
the ones in the wadi up in the north LINK they will link and they willink sometimes behaviour changes per area plus they will aggro but in the way like spiders aggro only whe you get super close for a decent epriod of time also they love egg salad and also they own a lot of **** and soemtimes try to peep in on your when you are taking a shower