earlier this year when i discovered the rail method i was a bit disappointed since i felt like the two years spent on the hammer method was sort of obsolete. after a couple of months of lessons with the rail method i realized that the hammer wasn't so much obsolete as it was a stepping stone.
both methods are capable of achieving positive results and they basically do the same thing but in a slightly different way.
The largest difference between them is the role of the wrist. the hammer basically teaches you to "slam the wrist open" to get the edge around. the rail uses the shape of your path to get the edge around and while there is some wrist movement, it is minor.
as a training tool, the hammer is more valuable since it teaches you how to control the disc's weight shift and how the arm moves independently of the shoulder (while the rail doesn't provide similar indicators).
in both cases, your basic goal is to get the purple shaded section of disc to the front.