Many machines have stitch formation issues when a floating foot is used, particularly if it is too high off the surface. The machine that the westalee demonstrations are done on looks to me to be a Viking and may have a special setting for using a floating foot, the Sapphires do, don't know about hers.
Two of my machines are only happy with the floating foot if I lower it so that it is almost touching, which is quite a bit lower than where it gets set if you use the shim that came with the foot to set its height.
You might look into the Janome convertible free motion foot, I use that one on my Brother PQ1500s. For ruler work I also had to buy the frame quilting foot set to get the ruler foot that attaches to the convertible free motion foot. That set up has a thumb screw that allows you to adjust the height in tiny increments, which is handy when coming to thicker seams that would otherwise cause it to hang up.
Rob