Janice you might want to try my test!!
http://good-times.webshots.com/album/569415726bHNKHF
Try the test and see what works best on your machine.
Remember that it doesn't really matter what your seam allowance is! What is more important is what your block measures after the seams are stitched!! That can even be affected by the thickness of your thread as well as the thickness of your fabric!
Try it with a finely woven fabric like a batik, and use a fine thread (I especially like piecing with MasterPiece by Superior) to take your measurements. Then try it with a thicker thread like King Tut. See if there is a difference! You may need to switch to a "scant" quarter inch seam allowance!
With as many little pieces as Sue tends to have in her designs, it is extremely important to measure your finished blocks as you go, and make corrections to get the right size.