Now, Bernina is saying the Dual Feed is for 2 layers of fabric. The Walking Foot is for more than 2 layers of fabric.
I did an experiment. I created a quilt sandwich and sewed from one side to the other in 3 different ways. I pinned the layers together at the end I was going to end up at. #1 was with the regular #1 presser foot -- it made a huge pucker on top. #2 was the Dual Feed -- it also made a pucker, but not as bad as the #1 foot. #3 was the Walking Foot -- no puckers.
For me, I really really love my Walking Foot. Don't know how I sewed without it. I use it for sewing Minky, flannel, denim, leather, vinyl, bindings, many layered items, and machine quilting.