I am not sure where I read it, but someone mentioned that one should be careful about piecing backs because of the tension that is placed on the seams as they are loaded, quilted, and worked through the quilting process .... it has taken me a few days to reason this out, but .... here goes!
The front is pieced ... with LOTS of seams, going all sorts of ways, even at a bias (as in HST=half square triangles) ... so, piecing a back is not different from piecing a front, but the one thing I would mention (if I haven't already) ... try to keep your seams away from the middle of the quilt, either horizontal or perpendicular ... the reason being, this is usually the place the quilt gets folded on the most. by keeping the seams away from those areas, you should have a seam that holds up a lot longer. <wave>