SoFine is thinner, and doesn't really have a sheen. It's draw is that it will blend in better. Superior's Omni is a little thicker and is what I use most on my HQ Avante. It does have a bit of a sheen.
One little thing that I learned from attending HQ training, is to realize that my quilting machine likes to go from left to right (right to left when you do pantographs from the back). So, if my thread is breaking, I can turn the needle a little to the right. If it skips stitches, I can turn it a little to the left. Turning the needle slightly to the right has helped me a lot!