Has anyone been mean and used backing width same as quilt top? if so has it worked?

This usually will not work. The quilting process will shrink the tip, back or both. The extra width is to allow for this. I have also never been able to line up the layers perfectly. Best to allow some extra.

If you are talking about when you send it to a long arm quilter, I wouldnt accept it that way.

JCquilts is correct. It is difficult to place to top/batting/backing perfectly tog to quilt if they are all the same size. If it is a small piece (like a placemat)you might get away with.

If you are taking it some where to be quilted, then the extra fabric is needed on all four sides to attach the backing to the frame and to give room enough for the base of the machine to travel freely.

dont do it--youll end up trying to tack bits to the sides--can you tell voice of 'you learn by your mistakes'

I agree with the others, ou will probably regret it if you don't have the extra.

Very interesting, I am self taught, and this is the only way I do it. I line everything up then I put my binding on first and then quilt, but I only hand quilt. And I dont do anything elaborate usually geometric shapes or outline blocks with embroidery thread. I get batting that can be quilted 8" apart so I don't have to be very close, although I am normally about 4" apart in my quilting. My focal point is the colors and design I use for the quilt top, not the quilting itself.

thanks for comments so far, I hand quilt everything.

I have never done it except for maybe practice sandwiches. Depending on what you're making you might be able to make it work but I agree you'll lose a little bit of your quilt that way. If you run out of fabric for your backing you can always piece your back. Add a border to it or literally, piece the entire backing. ;)

Piecing the back is a great idea, but I wouldn't add a border to it without cutting down the piece you already have by a few inches on all sides.

Otherwise, there's the chance that the border seam will fall at the same place as your quilt top edge and will lead to extra bulk when you put on your binding. Plus you might just get a sliver of the other fabric showing on the back (which would look weird).