See the picture? When the quilt is rolled as you are quilting, what is on the outside of the machine's throat is now inside, cutting down on your sewing space. You CAN avoid that by sewing upside down though :wink:
Also, the amount of sewing area shown is not the amount that you can actually use... look at how close the end of the frame is to the side of the machines throat.
How big your throat is will determine your quilting space on the frame.