Some weeks back, there was a discussion on the yahoogroups software-testing list, into which I managed to dare to comment.
The discussion, shortly summarized, was handling testers scope and authority, and what a testers should do that is within her authority. There was a comment related to the idea of separation of concerns emphasized in agile, where the "what" questions belong to business and "how" questions belong to the team. And a tester is part of the team.
I find myself and a significant portion of my colleagues in test to be people who are somewhere between business and the team. I've intentionally chosen to be a tester, and focus most of my energy into testing type of activities. I could be a project manager. I could be a product owner. But, I'm a tester.
If I would choose to be e.g. a product owner, I could still test. I could take the bits from XP and interpret that acceptance testing, at least the tip of it after all the automation, belongs to the customer role.
I see the potential personal benefits in focusing on one or the other of what / how – getting to actually be good at one instead of trying to do both. But again, mostly from a personal point of view, do I really have to choose between the sides I live by "living up to my role"?