I made the dressing with sour lean and it was light and the right texture for dresssing.
I agree about making the dressing thinner. I also thinned with milk, but I thought that still the texture of the dressing for the salad was wrong. All the sour cream made it so heavy. I'd keep the goat cheese -- a nice foil for the cherries and chicken -- but I might just dress the greens ahead of time with a lemon vinaigrette before layering on the cheese, cherries, chicken, and nuts.
I'm not sure what consistency the dressing is supposed to be, but I found it to be very thick. I thinned it out with a little milk. Otherwise this salad is absolutely delicious!