Well, I've got 'em up to 11 x 14, and at the largest size I have, it seems to be ok. I don't use it much because there is no easy way to set the borders of the image where I want them to be, and don't always like the aspect ratio that 11x14 affords.

I'd love to find one for 4x6 with a 1/4 inch border all around, but I've never seen one that size.