I can tell you that has been verified a number of times. Neva Parker mentioned it in her AHA seminar last June. It came up in a question I asked to Dr. Clayton of Lallemand many years ago in HBD's "Fortnight of Yeast". (http://www.danstaryeast.com/articles/yeast-growth
). The basic mechanism is that the same enzyme, acetyl co-A, is responsible for both yeast growth and ester production. If it's doing one, it can't do the other. So, if you pitch the right amount of yeast, you get cell growth but reduced ester production. If you pitch too much yeast, the enzyme produces esters because it doesn't need to work on cell growth.