I don't think there would be much argument against stating that the Hoover 150 was probably Dreyfuss' most new and sensational design.
Somehow, I get this "feeling" that Dreyfuss may have been involved with some minor Hoover embellishments as early as the mid 1920's. For instance, consider the DPI orange bag logos and motor cover bands dating back to 1926 with the advent of the model 700.
Please feel free to correct me, if my thoughts are wrong, as some valid citations will be noted and most appreciated. Thanks in advance.