Like @mischa43, I've been testing both Zen and Orion browsers. As a Mac user, I would love to switch completely from Arc to Orion. However, Zen offers a crucial feature that I value: the sidebar shown on hover.
I believe this functionality is a defining factor not only for me but for many users considering the switch to Orion. While I understand the commitment to following the Human Interface Guidelines, I agree with @somebody12 that some exceptions can be beneficial. Certain features that users are already familiar with or desire in their browser of choice deserve consideration, even if they slightly deviate from standard guidelines.