I have a 6600 and like it a lot, although it does have it's own personality compared to my older model Pfaffs. It is a big machine with a nice throat for quilting large items. It is a strong and can sew through a lot of layers easily. I like the needle down feature. I do not do a lot of applique so can not answer to that. On a negative, I almost always have to use "leaders" when sewing any seam at all. The feed dogs definitely do not catch like the other machines I have. Also, the bobbin case gets very linty and has to be taken apart from time to time to clean. By this I mean unscrewing the whole bobbin case area and cleaning deep inside.