The RayWay method works great, I've used it on two quilts now. It's even better if you use a double-layer of insulation. Then you can offset the top and bottom basted seams for more stability.
Also, Jardine recommends quilting, especially on large quilts. I do it on all my quilts, no matter what the size, as he claims is stabilizes the insulation better, especially when stuffing in a stuff sack. Some find the quilting unsightly, but it doesn't bother me.
Quilting is probably is more important if you baste two insulation layers together, as the basted seam is not particularly strong.