The biggest benefit of this set-up is that it doesn't take up as much space as a full-size longarm. I don't know if you can put the ProStitcher on the Simply 16. You could get the back handlebars and do pantographs. And you could get the Ruler Base and do ruler work -- my favorite quilting method at the moment. I really think you could quickly baste your quilt sandwich on the Simply 16, before you do the actual quilting.
I have the Avante' and wish I could have got the Amara or Fusion. Go as big as you can. The bigger the frame and machine, the faster you can get a quilt done.
HandiQuilter is a great company!