Been section leading for quite a while by now, both A and B.
Pros: - Pair programming will prompt more communication between students. Explaining your code to somebody else significantly helps in writing good code. - Students who feel lost can talk to their partners, thus freeing up the LaIR queue. - Less assignments for section leaders to grade.
Cons: - Working as a team is harder than working as an individual. I think it's would actually be easier and faster to do 106A assignments individually. - Each student still needs to do, or at least, work through every part of the assignment in order to fully understand a concept. When students work individually, I can see what concepts and techniques they understand and what needs improvement. I'm worried that working as a group will obfuscate this. I'm worried, for instance, that one 106B pair might successfully compete the recursion assignments when only one partner really understands the concept. - Students might pair with people of significantly different ability. This is more of a problem for A. Karel and Simple Java can be a 3 hour assignment for some students and a 15+ hour assignment for others. Ideally rock-star students paired with a struggling students would help explain concepts and prompt growth, but I'm not sure how this will play out in reality. - How will students collaborate on assignments? I don't think they should learn Git in 106A, maybe 106B. E-mail assignments back and forth is a hassle, and if they start using things like google docs, or pastie, some will inevitable be made public on accident.
Overall, I'm not a fan of it. On one hand, finding sufficient numbers of qualified section leaders is becoming a challenge, but I don't think it is that much of a problem. I've led sections of 13+ people and it was manageable. Moreover, this quarter all 106 section are less than 8 people, so section sizes are even smaller that they've been lately (though spring quarter usually gets lower enrollment).
For years we've had more or less the same106A/B/X that other teachers, students, and employers can count on to serve as a foundation of knowledge. I don't think disrupting that is worth the practical gain of less assignments to grade.
That said I do look forward to section leading this quarter, and I really want to make the most of this change. I see the potential and I want to take a crack at making it real.