and I like the effect, then I outlined the machine applique vine very close to the vine (like in- the- ditch quilting) and quilted a cable in the top and bottom borders.
I had filled the centers of vines with my initials and multi-colored flowers, all done in outline embroidery( much like Redwork) so I decided not to quilt the background of the vine borders with a filler design (which I probably would have done if I had hand quilted.) I did once see a photo of a quilt that was machine quilted over outline embroidery designs but I guess I'm just not brave enough.
The machine appliqued vine border is inspired by the vines found in a mosaic floor from a 6th century synagogue at Naro in Tunisia. I used to work as an archaeological restorer, though never on mosaics (pottery, stone and once, Roman glass) . I love designs from ancient mosaics-years ago, we spent almost a week walking around Pompeii (the frescos are also wonderful). Ami Simms wrote a book "Classic Quilts:Patchwork Designs from Ancient Rome" years ago featuring designs from mosaics but she dealt with patchwork not applique designs.