I just finished (this summer) a king size quilt doing it this way. It was still a monster especially when I was attaching the last one or 2 sections but I got it done.
Good luck with yours and post a pic when you're finished!
Glad to hear that it worked on a king-size quilt!
I was wondering about the stretching factor of the two top pieces: sounds like I'd need to stop quilting a little ways back from the raw edges that are to be joined so I'd have enough space to be able to pin back the batting & backing without stressing the to-be-joined edges. Then the top's SID lines would be continued across the newly joined area, right?