I, too, have the Janome 6600. It is by far the best machine I have ever had. It is a workhorse. I've had it serviced twice in 10 years. It does not have the Serpentine stitch but it can be programmed in. I also do not have any thread issues. Yesterday morning I was using a quilting thread, in the afternoon a very fine invisible thread. I did not have to adjust the tension in any manner, just went from one thread to another.