Vaughn and Scott,
I initially went to the Bostick-Sullivan website to look at the 11x14 frame, and that is when I realized that the image exposure areas are actually larger than the frame size. You are right, getting the bigger frame makes more sense. Plus they also have a 10% off sale until Jan 1, 2008.
As far as the addiction is concerned, I think it's already too late! After I started using the 8x10 more (didn't have a backpack initially), I get the feeling that 4x5 is too small!