My solution was to find a used grace frame with a mega quilter at a really good price and try that. It even has a stitch regulator. It took me as long to load my quilt as it does to spray baste one. It takes a lot of space that I didn't want to give up. I could only work a pattern that fit in the small area that the throat of the machine covered.The biggest draw back though was that I didn't enjoy quilting on it as much as I had on my DSM.
I finally decided on a sweet 16 sit down machine. I do have the stitch regulator (it does work really well once you know how to use it) but I found that the machine is so easy to use that I don't need it. My largest quilt so far is a queen size and I had no problem with that and expect that the king sized that is getting pieced now will work as easily. I pick up different kinds of thread just to try them and it works great on everything I have fed it, from 60 weight to 12 weight in cotton or poly.
I have table space on either side of my machine to hold the quilt and I work in a puddle so the only fabric that I am pushing is that small area between my hands. I do mostly FMQ and I am learning to use rulers. I really love to use it and it fits nicely into my sewing room.
I still don't like sandwiching the quilt.
Try different options before you decide. I am sure one will feel just right.