I bought my Innova, 26" on 12' frame, about 14 years ago. Innova was a pretty new brand at the time. It had a stitch regulator, but this was before the lightning stitch regulator came out. I was a fairly new quilter. I had quilted several large quilts on my DSM by quilting in sections, but I didn't enjoy that experience. A few years ago I upgraded my machine by adding lightning stitch and the new hook assembly. I do all free motion custom quilting, for myself and occasionally for the guild or close friends. I've never regretted buying the Innova. I've thought about adding robotics, and would definitely add it if I were quilting as a business.
One of the things I disliked about quilting on my DSM was basting the quilt sandwich. That would be my reason for not choosing a sit-down machine.