I haven't used the dual feed on the Unity, but I did play with the Quest when it first came out. Pfaff didn't renew the patent and Babylock used it for the Quest. The Quest and the Pfaffs with IDT were the only machines I found that would sew certain leathers. The Quest didn't sew that much differently than my Pfaff 2170. In fact, the Quest would use Pfaff 9mm feet.
If Babylock has followed the same engineering quality, either go to a dealer and try it, or try using the newer Pfaffs.
The newer Pfaffs with the drop in bobbin seem to work well with IDT. Pfaffies love them. I don't like drop in bobbins, I prefer vertical.
It does well on piecing, but I would invest in a single stitch plate or learn to use scraps to begin stitching. Any wide zigzag stitch plate will drag fabric in, regardless of design.