Honestly- many of us do FMQ on relatively nondescript machines. I learned on a dinky mechanical Brother. The feed dogs didn’t drop and I never covered them. I can successfully FMQ on a vintage machine. I like my relatively inexpensive Brother PQ1500 for FMQ. It is mostly mechanical. I’ve never had tension issues. It likes most threads even cheap serger thread. Once you get any machine that works you will still need to learn a it’s quirks and practice. A machine that works is step one but it isn’t the magic Bullet. There is a Baby Lock sister machine to the Brother. Maybe check it out.