I rolled at a metal festival the past summer just to try if it would work together with MDMA. It didn't. And it's only for a small part because of the music (music appreciation goes up with MDMA, and that goes for rock/metal/punk too), the main reason is that drugs are much less accepted in those subcultures than they are in the electronic music subculture. There's a lot of alcohol and weed so a lot of very messy people, but almost no harddrugs except the occasional coke user but even they are very few there. I ended up going to the camping grounds with some mates and continued our roll there. It really didn't feel right. Not that anyone gave me funny looks but it isn't really an atmosphere or environment to roll in... Your question is about pop punk, punk rock or post hardcore but I think the same applies there. It's just what I (and other people that tried it on seperate occasions) have experienced so keep in mind YMMV.
If you aren't scared to get some funny looks, don't care about them or if it is an event where drugs are more accepted (don't know if that's the case with punk, it isn't really my kind of music but I doubt it) I'd say try it out yourself. If this is an important event for you and you don't want to risk the MDMA killing your night a bit I'd say don't try it and leave it for some other event in the same genre to try it out...