I bought my Sweet Sixteen in March and really like it. I wanted the additional harp space but not the frame so it works well for me. I did not purchase a Tru Stitch (the HQ Stitch Regulator). Since you are already free-motion quilting on a domestic machine, I assume without a stitch regulator, I don't know that you would need the Tru Stitch. To me it is training wheels - and I didn't want to spend $1,000 on something I would outgrow - I would rather learn to coordinate moving the quilt and quilting speed from the start.
Cheers, K