I've worked in a variety of environments, and the most important thing in my experience is simply to ensure that your team is creating a working, tested, and "shippable" update every ~2 weeks. It amazes me how many teams fail to do this, despite calling themselves "agile" and "customer driven".

Use whatever methodology, technology, and processes you need to accomplish that singular task. Orient your entire organisation around doing that. Your customers don't care how you do it. They just want frequent updates and progress. And if you're not giving them useful updates (you'll know, they'll tell you) then the problem isn't methodology, it's probably your ideas. No methodology will fix that.