I just received mine in the mail Saturday and yes it does make a huge difference.
I have a Janome 1600P-DBX, for free motion quilting you cover the pressure feet with a plate that comes with the darning foot. There is a slight raised area that I thought would bother me with the Supreme Slider. Not so.
The Supreme Slider with a pair of gardening gloves works wonders for FMQ.
If you have any questions about it, please do not hesitate to send me a PM
Julie