I haven’t read his blog, but I have worked his method and had good results. In his books, Tempest says he created the pathworkings in conjunction with the angels themselves, and Theodore Rose makes a similar claim in LHD, (Damon Brand says the same in his books as well) so I personally see no reason to disbelieve one over the other. 
Coming from a background of ceremonial ritual, I originally thought visionary magick was too simple to be effective, no matter if it was Lucifer and the Hidden Demons or Raziel’s Paths of Power, but my experience had proven me wrong.
While I find the pompousness of Theodore Rose to be quite off putting (“only we have the keys to the true Lucifer, and all the thousands of other magicians are dealing with thoughtforms and egregores, blah, blah, blah” 
) he does have some solid information in his book, some of which actually confirms some conclusions I have come to on my own.
Aren’t we all? 