Peter -
My notion of "impact" is pretty limited. It's about those courses serving as antecedents to ANGC, Crystal Downs, Rancho Sante Fe and some other late Golden Age courses. Lakeside and Pasa (Royal Melbourne and Kingston Heath probably ought to be added), I think, pointed the way to those courses and the direction gca might have taken but for the deep, twenty year slumber the profession entered in 1932. When people awoke from that slumber, you had a new set of architects, new economic conditions and a very different popular mindset. So whatever impact they once had, ended at that point. (The "minimalist" movement in the last 15 or so years revived some of their impact, imho.)
So I'm not trying to make broad, sweeping claims for "impact" here. There is no question, however, that those courses were and are underappreciated in the history of gca.
Bob