I just got my new tires, 265's with factory sipes, I have about 600 miles on them and the backs are already wearing the sipes so there is one raised edge. With all the torque it is really hard on the tires. Has anyone else knoticed this??

That will happen everytime on these trucks. What I would do, is to X rotate them and that will take care of the issue. You need to change the rotation of the tires to get that irregular wear out of there. Should not hurt the tire in any way.
Good Luck.