My Janome 11000, 1600P and 3160 QDC all freemotion well for me, with and without the blue bobbin case. I don't go really fast with my machines when I FMQ. I noted when I tried to really speed, especially with my 11000, I had issues with bobbin tension.
I really like my Janome machines. I also have good luck FMQ with my vintage Singer 301's, Featherweights and even the treadles.
I hope those experiencing problems get them sorted out. It's so frustrating dealing with tension issues.
And in case you're wondering why I have ALL these Janome machines, the 11000 is my "go to " machine, the 1600 is on my Grace Pinnacle Frame usually, with the feed dogs removed for now, and the 3160 travels with me back and forth to the trailer. It's overkill I know......:)