Just wanting an opinion to help focus my study and practice efforts. What would you folks suggest is a minimum level of chord knowledge for a guy who wants to be very proficient as a Blues / Rock / Roots Rock rhythm player. I think that Root/ Five power chords with roots on the 5th and 6th strings, 4th Diads on all strings, 7th and 9th chords, are what I have on my list. Can you add anything else that is cool / useful to the list??