If you do not have enough spine angle, you are going to run into problems period. From my understanding of Hardy, one planers move the arms more around the body, two planners more in front of the body. In a one plane swing, the arms and shoulder move on the same plane with a steeper spine angle. In a two plane swing, the arms move more vertical and independently of the shoulders which have a more horizontal rotation and the set up requires less spine tilt. The club should still move back on the plane from which it starts out. However, because the address position in the 2 plane swing is more upright, the plane of the club is more upright and visa vera. I think it depends on what you naturally do. IMO, If you tend to take the club back on a flatter plane, you might want to consider adjusting to the mechanics of the one plane swing.