Djab: I agree with previous comments N2M2P1 and then N1 instead of R1
d4rkm4tter: Both N1 and R1 sequences are in the problem, it is nice to see unter the stones played out and I disagree that the opponent has to always play optimally. Sometimes the most interesting sequence is worth including as well.
I would say L4 or N2 is the biggest move here.