I still feel that way, but after reflection, it occurred to me that the question was more about what it would look like. If you're looking to reproduce exactly what I did, then no, you can't switch fabrics. It will look different if you use different fabric for the setting triangles than you did for the block background. Using the same fabric floats the blooms on the quilt.
However, if you're not looking to reproduce exactly what I made, have fun with it. I fired up EQ7 and colored the triangles differently to give you an idea what things could look like.
I rather like it this way. If I ever make this quilt again I think I'll choose different facbric for the setting triangles. It's a little less modern, but I like the way the triangles bracket the center. I also like the darker shade of the same color for the binding in the last two examples, to frame and contain everything.
So go ahead, play with color! I'd love to see your finished quilts. Please share! Would it help if I started a Canuck Quilter facebook group?