I've got the Simplicity. I usually put strips through on the grain rather than bias. I can do either a quilting fold in 1/2 or use the attachment that does double fold. I will use double fold for sashing and applique. I've framed rectangular embroidery pieces on a sweatshirt with double fold, and it's stayed put for almost 20 years. I only use bias if I need it.
The bias makers - manual and Simplicity don't care which way you run strips through. Just trim and flatten joins well.