I've used Janomes all my life and never had one that fussed about thread. That said, if this is for embroidering motifs, I think that is a different thread weight so the whole thing doesn't get so thick. Which would be a pretty big investment because you need to many colors for embroidery, it all shows, unlike just buying base neutrals for piecework.
Perhaps someone will chime in on what their thread investment has been... sizeable I expect.