I have purchased it though I can't say a lot about it .... have only used it for minimal practice yet.
The joy is that you do not have to adjust your tension settings.
The other thing that I purchased was the better FMQ foot, that gives you more of a "foot" than the traditional darning foot. There's actually three different feet in the package, and the one that I was directed too was th plastic one with the circular bottom on it ..... it worked like a dream, compared to anytime I had done FMQing in the past with the regular darning foot. Again, I've only done a wee bit at this point .......... I was totally impressed, and so was a friend who decided to buy the new foot.
Get your shop to give you a demo and let you test drive it before you buy!