I do like that purlbee one. I have never learned how to cut using the lines on the ruler. I think that the one beginning class I took, the teacher was left handed. I find that I cut completely opposite the tutorial, just with my right hand. I'm going to have to learn to have the excess fabric off to the right instead of to the left. I like the idea of the ruler "protecting" the square that you are going to use in the top. The way I cut doesn't do that and if I veer off somewhere, I've ruined the piece.
I hope it's not too hard to retrain myself. I've been cutting the wrong way about 6 years.....rrrrrgggg.