I’m 6 foot, and a couple of weeks ago I bought a medium based on Brant’s recommendation in this thread: http://singletrackworld.com/forum/topic/on-one-codeine-sizing
I also went for the ccdb upgrade. I set it all up to the recommended settings, and it’s working great. (I also added a reverb.)
I’ve been riding a 456 for the last 3 years, so this is a very different bike. The whole package is a joy to ride. It’s fun and it’s fast on a variety of trails. I added a OneUp 42T range extender and I can climb the steep hills in my local woods without any drama.
With a short stem the cockpit is quite compact, but it’s a lot more bike than I’ve been riding, and having gone for the smaller option it still feels nimble enough to me. I haven’t tried a large and I haven’t been for an all-day ride yet, but I’m very happy with the medium so far. It’s a great bike. Enjoy it!