When I purchased my 440nq last year I was informed the 550nq just a face change. I would have purchased it if the throat had been enlarged. I decided on the 440nq well before that having been using a friends and loved it especially the BSR which made free motion so easy. . If you can get the 440 with walking feet and BSR all in one package I'd say have it. Bernina sites do downloads of leaflets of machines.