If you get comfortable in adjusting tension and choosing the right needle, your machine will like a lot more threads. Some machines are adjusted at the manufacturer or repair shop to a certain thread, and if you want something else you might need to adjust the needle and bobbin tension. It is a myth that a machine has “automatic tension” and it is also a myth that you can’t adjust the bobbin tension, I am not saying you shouldn’t be careful, but if you know what you are doing it will be fine. I have had Vikings and Berninas, and I have adjusted the top and bobbin on both though it is easier on the removable bobbin cases like the Bernina has. It is one of the reason I prefer front loading bobbins to top loading, but it can be done on either. I use invisible, metallics, cottons, polys, in various weights.