Well, it was a while ago that I ran this (it was the weekend after my Tri) and I figured just so I had a record somewhere I'd say what my time was, and my experience.
I chose to run the 8k, which is 5 miles. My goal was to be sub-45 minutes, since that would average out to be less than 9 minute miles. Then I met the elevation- without my inhaler, lol.
I ended up with a 49:38 or something like that. Less than 10 minute miles, if just barely, but I did finish it, and didn't walk or anything. I felt like I would die the whole time. Ironically, my legs felt springy. My lungs just aren't built to face these hardships- the change in elevation was quite a shock for them. But, I'll just keep trucking.