I guess it turns out to be personal preference for the process and results. I have a lot of different threads, not "married" to one brand or weight. I'll use whatever works best on a project in my machine. So far nothing has fallen apart (and I even press seams open!) and I really don't expect my quilts to be around in a hundred years. I heard a presentation by a YLI thread representative a few years ago and she said use what you like that works in your machine.