For a thicker line, I usually use 40 weight, however, I normally use 70 weight, so there's a bigger difference for me. I choose my quilting pattern carefully because I don't like the look of a lot of backtracking with the heavier threads. I don't know if I actually split the previously quilted thread when I lay down a new line of thread or what, but it looks messy to me. I try an use a quilting design with not a lot of backtracking. When I use the heavier thread, I often use the same color in the bobbin, but my normal 60-70 weight. I'll have to look up the brands...
I think you will have to experiment a bit.