Thanks for the review! I must say you have summed up many of my own thoughts on it in a way that I never could have. I certainly found the vagueness over the actual practice and the lack of description of it in the book somewhat frustrating. Subsequently I have discovered that Karl Weinfurter's Man's Highest Purpose (available here) has a more detailed description of the actual practice on about page 90 and talks about how it connects with chakras and mudras (he believes Krebs' system was developed independent of any Eastern influence as Eastern texts hadn't made their way west by that point).

You will certainly find Krebs' approach very different, though also a bit vague on specifics. ;-)