Project and product managers are often thought of as fundamentally different in that the former sometimes has to "protect" the team/project from what might be considered unreasonable changes or requests coming from the latter (not to suggest that it's an adversarial relationship by any means, but there are certainly potentially conflicting interests at play). With that in mind, what do you think would be some of the biggest challenges of switching from project to product management, and what can we do to address them?