My Janome 11000 has the lock stitch. I've used it a lot, but lately have decided I like the look and feel - no bumps - of burying the knot better. As I become a bit more experienced at quilting I also become a bit more discerning and critical of my own work. So, I am way more willing to take the time to do things like burying threads. But the difference is really pretty small, and as everything else in our wonderful craft, it is totally a personal decision.