Helmets & Helmet Suggestions

My concern would be that it would take a knock that would render it unfit to use and that I would be unaware of that having occurred.

Precisely. And the chances that a helmet left bolted to bicycle "takes a knock" are extremely high. Bicycles parked in public get routinely banged-- and public ranks don't decrease but perhaps even increase the chances. The only "safe place" to keep a helmet during a commute is on ones head.