The 440 generally comes with a Bernina Stitch Regulator while the 430 generally doesn't. If you want to free motion quilt and need the help, the BSR is nice. I have a 440 with a BSR and have had no problem with it at all. I think of the BSR as training wheels. I don't need it now, but it helped me tremendously for the first few years of FMQ. Mostly it gave me confidence. The price is good. The 400s are being replaced by a 500 series.
Pam