I have a BL that has that thread cutter and I really dislike it! Yes, when it works it leaves a little tangle on the bottom....dealer calls that an automatic knot(ha,ha)...... But most of the time, if I cut thread, then start another piece, if I don't get that fabric to engage immediately with the needle with that first stitch, it will unthread itself on that first stitch because the tail it has is so short, it sucks itself up into the head....then have to go thru the whole ritual of retreading, auto needle threader-another pain in backside......not happy and dealer has moved about 25 miles away, in a direction I don't often go in......but one day, I will pack this baby up and leave it at their doorstep! Ok I feel better now that I have vented!