One change I'd suggest: drop the use of the term "sprint". Prefer "iteration" instead. Talking about "sprints" is a bad metaphor, and the metaphors we use do shape the way we think and act to some extent. IMHO, along with the "gap week" between iterations (which I vehemently agree with), this is part of avoiding the conditions that lead to burnout... if you're sprinting, sprinting, sprinting, all the time, bad things are going to happen. Not everything you do needs to be at balls-out, breakneck, full-sprint speed.