It is frustrating when there is conflicting information about using the walking foot. My LQS where I purchsed my Babylock Espire said I shouldn't have used the walking foot for the zig-zag stitch (I ended up with very inconsistent density of the zig-zag stitches--a few inches of really dense stitches then a portion where the stitch was nicely spread out and back again)--it should only be used for the straight stitch. That seems a bit limiting.
Also, when I use decorative stitches, the machine moves around the fabric so much that it is virtually impossible to keep it going in a straight line so I only used zig-zag on my most recent quilt as you go quilt.