Hi RAc Please take this with a large grain of salt, because I'm only discovering the differences for myself ...   Oh yes, I'm familiar with Kurt's essay.  And I've discovered the 4th finger's use for the Crane 4th.    But if you play in the style that the Sallie Army book lays out and in keys that you mentioned (C, G and D), you only use the 4th finger, at the most, twice for C# and F# in D.  You can still pretty much stay on the 1st three fingers.   When I got