I can’t really speak to Scrum because I’ve yet to participate on a project where Scrum is really being done (a team I’m on at the moment is doing something Scrum-like, but it’s not proper Scrum), but I can say that personally I’ve been on a team at AOL where we did XP and stuck as closely to the practices as we could, and it yielded really good results for us.

The good thing about Scrum is that as long as you actually DO your sprint retrospectives and adjust your process to eliminate things that don’t work and implement or improve things that do work, then over long enough time windows, you’ll be better off than when you started.

But, like my Karate Kid analogy, you NEED to do the practices as prescribed in the beginning, long enough to master them until you gain that understanding that comes with experience and mastery to know how to best tailor them to your specific team, your environment (business, culture, etc.), and the special needs of your project.

But, yeah, you need to get the team to buy in and DO the practices as prescribed long enough to get to that point… which is where an outside coach that keeps everyone focused and honest might be really valuable.