My thoughts and they are just that, are 2s2p packs are more likely to puff prematurely. This is based on my own and buddies I race with running both 2s2p and 2s1p packs in a safe non abusive way. All packs treated equal, ran in similar classes with similar motors charging at similar amps, the 2s2p just have seemed to puff quicker, and more often. This hasn't bees totally brand specific either.