I have one for my 6600 and use it for FMQ and piecing little pieces. I have a system to remind myself when it's on - I flap down the panel that shows all the decorative stitches, then flap it up when I put the regular needle plate back. I can FMQ perfectly well without it though, though stitch quality is slightly reduced on intricate patterns. It won't solve every tension issue you ever had though. I was about to recommend you ask on the Janome forum but I see you're already on there. :-D