I would go to a larger quilt shows because you will find plenty of dealers with their DSM all set up. It is like buying a car, you got to take them out for a spin. I would bring some small sandwich quilts to use when testing.
I have quilted queen size quilts (my Avatar) with my Bernina 1530 that has a 7" throat and had no problem at all. The trick is to have support to you left and in back of the machine. Then you quilt from the center out. Have fun shopping!