I've had a White Superlock for many years and only used the 3 or 4 thread overlock, not because of the threading, but because of the manual tension stitch adjustments. I, then bought a used Viking 936. Again it was bear to get a nice rolled hem, for example. One day a friend brought her Bernina and her TOL Viking. We spent hours trying to get a perfect rolled hem on each machine to no avail. The next day I bought a Babylock. You choose whatever stitch you want, thread it, and every stitch is perfect. To me, having perfect stitches so easily was the deciding factor, not the threading. The only time I do a sample is try different thread combinations.