A rabbi I know once told over a story: He was called regarding a shiduch for a young lady whom he knows. The lady, who was the mother of the boy, called him and asked about the girl. The rabbi told him what a wonderful girl she is, how she is constantly growing and improving herself all of the time, and how her whole family is the same way, always growing and trying to become better Yiddin.
The lady then asked him, "But I heard that they're not so Heimish... Is this true?" The rabbi responded, "Do you consider your self Heimish?" She said that yes, certainly she and her family were very Heimish. He then asked her, "Are you growing?" And after some fumfering, she responded that they were basically happy with who they were.
"Well then," the rabbi responded, "I wouldn't recommend this shidduch to you. I don't think they would be a good match. After all, your happy with who you are and your Heimishkeit, while they're into growing. I don't think it would be a good match."