I don't have this particular die, but if you sew a seam that gives you the right size patch, I have found the accuquilt dies very accurate. I refer to the patch size because when you say a 1/4" seam, you shouldn't measure the seam, you should measure the resultant patch:
http://www.quiltingboard.com/tutoria...ce-t89997.html
When you look at the outline of the die on the accuquilt site, all the triangles have the little corners already clipped off for easy and accurate placement.