Thank you all for your thoughts.
zozee, I looked again and I was off on the model - it is the VM5100 - Dreamcreator XE. If it wasn't for the huge throat and what I think is a good deal, I'm not sure I'd be considering it. It feels like it will have a big learning curve for me. Maybe too much machine for the level I am at. But I haven't tried it yet and people say the Brothers are relatively easy to use.
The Brother throat is 11.25 x 5 for a whopping 56.25 square inches. The Janome 9400 is 11 x 4.7 for 51.7 sq in, the 6700 is 10 x 4.7 for 47 sq in, and the Juki I have is 8.5 x 6 for 51. I quilted a twin size with a flannel back and really had to shove it through the Juki throat. I thought it would fit through more easily. The 9400 is basically the same size.
I think I might take the last twin quilt I made to the shop with me, and see how hard it is to squeeze it through the various machines. I need to try to get over there this weekend.
I also need to remember that the few times I'll make a quilt larger than a twin, I could rent a long arm or pay to have it quilted. Not my preferred way, but once in awhile is OK.