My sister did one in CO last summer. It was supposedly the hardest one (or one of the hardest ones) they'd constructed yet. She, too, said the Arctic Enema was the absolute worst; it was near the beginning of the run, and she said if it hadn't been, she would have skipped it. It's several levels of magnitude worse than just cold water. I don't know if you've read about it, but you plunge into ice water (it's almost all ice, just enough water to let you move through it), then go under a wall, then you have to pull yourself up and out. Brrr.
She also got done and said, "It actually wasn't that bad, but I wish there had been more running!" She's crazy. She said the electric wires were not bad at all. I think they randomly supercharge a couple of them, and if you get zapped, you go down; otherwise, it looked like the people who just made a run for it did the best. Good luck! I'd like to do this next year. I probably won't be as breezy about it as my sister was when I'm done, though.