What foot are you using for FMQ? I have a Sapphire. It came with an R foot, which I didn't have any luck with. I do much better with a spring foot. I'm not at home to check the item number, but if you want me to check when I get back, let me know.
I can't advise on other machines. The Sapphire is my 2nd Viking and I had the first Viking for many years.