A top-left logo, linked back to the root page, is part of the design language of the web.<p>I suspect a proper A/B test, of users attempting to complete common tasks (as per Jakob Nielsen's usability tests), would find customers slowed by the logo's absence.<p>But by all means, collect the data. (I don't see data here except for an assertion that the overall page design works. Well, maybe, but test the specific suggestion.)