Derrick and Jack,
It is a 2 to 1 hauling system because there are two parts of line at the moving block (in this case, the Hitchclimber). The tail of rope through the Revolver is only a change in direction for the pull. Three parts of line there, but that 'block' is stationary.
Yes, it is descent on a single rope using hitches. However, I still have the tail redirected and giving some added friction, however slight, through the Hitchclimber and Revolver. So, it's not really descending on a hitch only... something that I wouldn't do.
Thanks for the comments!