I found this Youtube video that shows the Brother dream frame. Most of it is shown with quilts that fit within the width of the frame; not sure how easy it would be to do a large quilt as you would need to re-clamp quite a bit. It does appear that the stitch regulator is for Brother sewing machines only. Since the bobbin doesn't hold as much as a longarm, you would be changing the bobbin more often with this setup. I also wonder about tension issues with free-motion; tension tends to be more of an issue with domestic machines used on a frame setup. Usually you can resolve the tension issues, but you would probably want to be sure of that before purchasing. Anyway, looks interesting for small spaces. Here is the link:
https://www.youtube.com/watch?v=PVXbm6M684Q