Evaluating student participation through co-assessement

I've used co-assessment for several quarters for student participation, and I love it. The way it works is:

• there are two feedback modules on GauchoSpace: one in Week 5, another at the end of Week 10
• at each point in the quarter, students first evaluate themselves; they rank their participation on a 50-point scale, give themselves a specific score, then justify that score by checking off items they've done to deserve that score and adding additional comments if necessary
• I then review their scores and comments. If I agree with their score, I leave it as is; otherwise, I adjust it accordingly. 

The reasons I like this system are:

• it gives students a chance to reflect on their own performance and holds them accountable for it. In the Week 5 module, a lot of students mention their perceived shortcomings and state how they are going to make up for them in the second half of the course...and many of them do just that: they speak up more in class, come to office hours, etc. I think for some students, the mid-way point serves as a "wake-up call" that helps them do better in the second half of the course.
• students are generally satisfied with their grades. The grades they give themselves are usually very reasonable and in keeping with my own notes/perceptions, and in the event that a student is too hard on his- or herself, I make sure to give him or her a fairer score. 
• they do most of the "hard work" for me: all I have to do is look at the grade, decide if I agree, and move on to the next student. It takes less than 10 minutes per feedback module.

Does anyone else use co-assessment in their classes? If so, what have your experiences been? If not, is it something you would like to incorporate into your class, and how might you go about it?