Both of my grandmothers were quilters - one of them ALWAYS did separate binding, one of them ALWAYS brought the (heavy flannel) backing around to the front.
In my experience with their quilts, both wear pretty evenly but actually the separate binding is the only one I've ever had to repair. Probably because it's quilting cotton rather than heavy flannel that my other gran always used.
In my own quilts...Funny, I never thought about it until now but I guess I sort of subconsciously follow their examples because if I use flannel for a backing I tend to bring it forward as binding; and if it's a quilting cotton back, I usually use separate binding.
In my eyes, both techniques are equally valid, equally good quality.