I consider myself somewhere in the middle between Chas and many that simply use the left hand to designate chords. Chas is right about LH comping being a learned process. I started when I played organ only, and needed some sort of rhythmic movement. I started with simple 9th,aug, 8th, and experimented. I started to learn running bass lines, but no cigar. I have started to use more piano for LH, and this is where it really comes in handy. Everything is a learning process, but one has to keep at it.