It's a hard one-- if my child were struggling in math or another core subject, I would be investing in tutoring center and spending extra time helping at home. Peer to peer is nice in that it can help with empathy, but it's a huge responsibility, and a child's learning time should not be taken with tutoring other students (my opinion).
Also, my DS is younger and intense. I would worry that he would start to become frustrated and eventually say something impatient to a struggling child. He's a nice kid and generally patient, but does not have adult reactions and adult empathy.
