I decided to cut my losses before the headline act and just enjoy their set, not least because the crowd were crammed right up to the stage. In better conditions, they would have been great to shoot - very tight, and huge energy.
Still, it wasn't a complete loss - for starters, all the bands were great. I managed to salvage a few images via Lightroom, and learned a lot about how far I can push my EOS 70D in challenging conditions like this. I'm looking forward to shooting The Hip Priests again in a venue that has, oh I don't know, maybe at least one spotlight pointing at them!