Glad to hear that these stories are giving you courage. I did a king sized quilt on my home sewing machine. I wanted a challenge.
I did pin baste the quilt and just took my time starting from the center out. I free motioned the quilt. The center is the hardest to maneuver but I think the trick is to keep the weight of the quilt off the area that you are working on. And than that, it is just persistence. (But isn't that the key to all quilting....even piecing.
)
Anyway, one reason I did a king sized quilt was to say that I machine quilted a king size quilt.
Good luck!