I too have issues with standing or walking so have explored this at several quilt shows and shops. The George is a wonderful machine, however, note that the orientation is the same as a domestic machine. The HQ 16 sit down has the orientation the same as a long arm and I found I liked that much better. I didn't like the feel of the Tin Lizzie. There was another machine made by Pennywinkle Valley Ranch that I really liked and is much closer to my price range. They have a web site if you care to look at it. I think it was called Smooth Operator.
Since this is a substantial investment, take the time to try them out in person. Good luck and have fun!