Just be careful of the fabrics you choose to form the window. For instance, even though you see the line with solid fabrics, the eye slides over it. However, if you were using a stripe fabric or some prints, it could take more effort to make a half square triangle that "blends" at the seam line, than to deal with the y - seam.
As in most things with quilting, both your tolerance for how a block/quilt will look and the final usage (utility as in not meant to last vs something you may be looking at for the next decade or so) can go a long way in making the choice for you.
Joyce in Delaware