I have the cutter on my Brother Innovis 4000D. I have to hit the button for it to cut if I am doing regular piecing or sewing. If I am in embroidery mode, it will automatically cut the jump stitches if the design has been digitized to use the auto cut function.
Mine only cuts the threads. If you want to backstitch you have to do it manually or use a machine stitch that includes the backstitch. I have to use leaders or hold the threads or my machine will eat some materials. It especially munches on very soft materials. I do have a single needle plate but don't use it because I use the inside of one of the feet as my quarter inch stitch guide. I have to move my needle to use the foot.