It's impossible for me to describe specific differences, as I heard them too far apart in time, but my gut feeling about the difference is that when I heard the 20, I was not even closely tempted to sell my Basis Ovation (upgraded to the functional equivalent of a Debut Mk V vacuum), but I was when I heard the 30. Something about it that just seemed "right" and unmechanical vs. the 20, which was pretty good-sounding in its own right. Fortunately, there's no dilemma for me as I can't afford it.
