Strike finders were a great value in avionics before Nexrad. In some ways, such as update cycle, they are still worth more than Nexrad. Given a choice between the two I prefer Nexrad because you get a larger picture. But if the going is getting rough I would actually prefer a strike finder because time counts when you are approaching convective activity.
Track up is the way I fly also and from what I am told, most aircraft fly that way. I have seen guys use north up who were smart enough to decide, but I could never quite see their reasoning.