A pen and paper would probably do just fine for taking the odd note.
However I'd probably take a cheap old laptop off ebay, bought for the event and then discarded afterward. I'd feel I was missing out if I wasn't able to at least dip a packet sniffer into the famously hellish torrent of exploits I've heard so much about. I'd never take any of my personal machines though.
One year I took a pocket-sized notebook and a slide rule. The next year I took an iPhone and a eee PC. I experienced the same level of hacking both times.
Always have an obscure old phone with almost no feature (except voice and text). Generally the OS is so minimal that there's little room for an exploit, and by little room I mean that you will not have enough memory to add your rootkit.
That works for you, it won't work for everyone. UMTS and LTE don't have the capacity to replace GSM, not even close, they can barely keep up with the growth of additional demand. GSM is broken and here to stay for a long, long time.
