Dave Haynie himself in an interview said he wasn't part of the 500 project as that was the baby of Bob Russell. George Robbins and Bob Welland were the lead engineers. Dave worked on the high end models first with the 2000. Jeff Porter was in charge of product development. Interestingly in designing the 500 there was a decision not to use the designers from Los Gatos responsible for the 1000 but to use the core designers from the Commodore group. Haynie was with Commodore at the time working on the C128.. think he was their lead engineer at the time. He wanted to work on the 500 but moved to the 2000 team.
The motivation behind the 500 was a low cost model. Not surprised it has a C128 flavour so most likely a Commodore old hat designer and not an Amigan in truth.
The actual case was designed by Herb Mosteller who also worked on the C128 case. There are some that believe the case was designed by an outside company. Difficult to say.
