Even if I am not doing SID I still like to start from the center of the quilt and baste in stitches. These help to stabilize the quilt sandwich, especially if you are wrangling around a larger quilt. The more quilting I plan on doing, the more basting stitches I like to use.
I have had a little traveling even when using the spray, and a little basting seems to help hold the whole project together nicely.
Any amount of quilting can draw in the quilt, distorting the final shape and seam lines. The heavier you quilt, the greater the chance. Keeping the quilting evenly distributed, and working from the center out, may help you too.
If you are straight line quilting, a walking foot really helps to feed the sandwich through easier, with less distortion. Try using a little longer stitches too.
You shouldn't have to really tug and pull on the quilt to get it going under the needle. If you have to tug too much, you run a greater risk of distortion.
The suggestions for supporting the quilt are great ones, and will be very helpful to you
