I just finished making Kwik Sew 3489, the DVF knockoff in a black/white rayon jersey. I really like it. These rayon jerseys are so comfortable to wear.
I cut out the dress in medium except small at the neckline and armscye. I added extra at the side seam and dropped the dart but did not do a FBA. Right away I could see that the dart was too low so I put it back almost to its original position. I think with a 4 way stretch fabric this occurs because the weight of the fabric pulls down. I needed to cut away the medium length at the waist back to the small length. I took in the sides so that it is somewhere between medium and small. I top-stitched the neck facing to try to keep it in place better. It still wants to flop out some and also the top-stitching pushed the fabric somewhat. So, to prevent that, on the skirt and sleeve hems I used Steam-a-seam to fuse the hem in place before stitching. That worked great.