The way I figure, whichever method you use, to move the tarp, you have to go to both ends. So (in my mind) the argument that it's simpler to move 2 prussiks vs. adjust 2 ends is rather null. Whatever, HYOT (hang your own tarp). :)
I've always used Linelocs, and they're dead simple to use, and I've only ever broken one, even in quite high winds, and that was my own fault.
Of the 2-ended camp,
PF