I have just completed RUGS2 and have to say that this is a very very useful book (I have also done RUGS1...and recommend it as well). The great thing about this book is the now I no longer have to memorize various chords but build them up through the principles you learn in the course. This makes things a lot easier and also gives you options in certain situations where you can use slightly different grips to achieve the same thing. This is a must have for all players.
Now, I do have one question that I cannot figure out. What is the grip used to make the open B7 chord and the open F chord ?