From what I have been reading lately, the concept of play is that play is optional, so for something to truly be play-based, a learner needs to be able to choose not to play. I believe that if a facilitator chooses to add a game layer to the curriculum, it could be difficult for a student to not be part of the game layer and participate in class in a more traditional way.
As you know, many games are based around the concept of direct competition, in the gamification circles we call this mechanic “leaderboards”. Such game elements, like leaderboards, I feel highlight the fact that some students succeed while others fail, which personally I think is a crap way of teaching. The same can be said for the old traditional public display of rewards (like the old gold stars approach). Students who are doing well can be driven to continue to gain more stars, while students who are struggling watch as their classmates accumulate more and more accolades while they are just trying to get started.
One advantage of an LMS designed for gamification is that the system can assist teachers in the design of a course. By embedding different types of reward-based and meaningful game-based and play-based layers, facilitators can easily try out different gamification techniques in their class avoiding the public humility of the students. The LMS can also provide information as to what types of game elements might be good for different types of class activities and what risks the instructor and students may face when using the system.
From my discussions with students, if they see a system that looks like a traditional LMS or outdated Web site, it has been discussed that the facilitator will have to work harder to help students realize that the class experiences are different and exciting. Whereas if the students come into a gamified system that looks like a game or has game mechanics, it can be said that they are more likely to approach the learning with an open mind and a playful spirit. Just food for thought.