Check out www.eyelinegolf.com Click on the videos button and then play the video titled "The Putting Plane Concept " There are also videos using a laser to demonstrate the "square to square" and "arc" methods as well as the "plane" method.
The plane angle used here is clubshaft, which in turn will create a much larger arc on the ground than LEFT SHOULDER.
Straight back and through is fine as long as the thorasic region of the spine is horizontal to the ground. By doing this you will use a dual vertical hinge.
If the spine is angled to the ground an angle hinge will be produced.
Trace the straight plane line and figure out where the movement is coming from. Is it the right shoulder, is it the right elbow, is it the wrists, etc. Mixing is dangerous because too many compensating movements are going on at once.
I was just throwing the eyeline videos out there for discussion. That being said, which one appears to be the most ideal? "Putting Plane Concept" "Square to Square" or "Arc"?
The heel of the putter rides along the 18deg. angled rail.
I don't see why 18 deg is such a big deal. Everyone should be allowed their own preferred plane angle, as long as they're tracing a straight plane line, and the heel or toe of the putter doesn't strike the ground before it hits the ball.