I've heard the same thing about the newer Singers. I bought a new Singer Touch and Sew 758 new in the early 70's. It has lasted until recently when the expensive gear broke - twice. I found a replacement gear with a slightly different design, but that leaves me to do the replacement myself. I haven't gotten the nerve to go for it yet. My Singer ha a fairly large throat, maybe a little bigger than my new Viking - embroidery machine, not the bigger throat model specifically for quilting. I've done king size quilts on both machines by puddling.
I would echo the other posters to go for a wide throat.
That being said, it's also possible to do qulit as you go on just about any size DSM. That's what I was going to try next, but I still have a number of wide backs. I've thought about doing QAYG by using the large back, and sewing on one row of the quilt at a time, piecing the batting into each row or two. That should work too.