I have the HQ16 Sit down and it's great . I already have a Bernina 730 with enough bells and whistles to last me a lifetime, I just needed more quilting space, and 16in is brilliant (it's also about 9in high from table to underside of machine)
I went for the Sit down because I don't have any room anywhere for a table/frame set up, and I can't stand for periods of time either. I am one happy bunny.