Don, I have seen that "rule," and I have a LOT of problems with it.
It was leaning against such an extension that once caused the base of a ladder to come free on me. I know, the movied always show a nice graceful transition, but this is the moment when the ladder seems most likely to move.
My own preference is for the ladder to project very little above the roof line, and for me to go 'straight over the top,' rather than shift to the side.
This arrangement of the 4-way does project a foot or so above the roof edge. The outstretched "feet" make it VERY secure, with virtually no wobble or shift as you make the transition.
Most important, the ladder is NOT leaning against a flimsy sheet-metal gutter. Besides being flimsy, sheet metal is slick .... which makes it so much easier for the ladder to shift.
Now, IF your ordinary extension ladder is securely tied off at the roof, AND the feet are placed in a manner where they simply cannot move on ANY direction, the "step to the side" can work out quite well.
A final 'detail" to consider is that the "usual" rules are written assuming "usual" ladders. This 4-way ladder is neither fish (extension) nor fowl (step).
