I bought my serger to sew clothing. I have sewn an incredible amount of dancewear with it (and costumes for dance theater groups). I would have to say that I would never want to use a serger on a quilt. I do too much "reverse engineering" aka ripping apart which is much harder to do with a serger becuase you have to deal with at least 3 threads more!
I love my serger and use it alot. I love my sewing machine and use it alot. Each does its job well. In my opinion for quilting only a serger is a big expense. I can actually sew anything I want without a serger (finishing seams might take longer is all).