I don't use most of those chords. What I want is something that helps me to be quicker at spotting what key we're playing in, more especially when we change keys in the middle of a set. Or when we're playing one of those tunes which keep on switching back and forth between keys.

And more particularly when I'm playing with a capo on some peculiar fret, because someone else is playing the guitar as well, and it's getting a bit crowded if we both play in the base position.