I would have to agree with BeerCan, on all points. Also, maybe have an extra pair of socks. With the length of the Talon, maybe two. And as with everything, waterproof!! As for the protection against Saw Palmetto attacks, I mean scratches, unless you like having cut up, bleeding legs, wear something. I don't, but I'm a little nutty like that.
The shoe thing, BeerCan is sooo right. It can be a pain to have to carry that second pair (sometimes you wont need or even get to) but the last thing you want to do is have to trekk a few miles in a pair of bike shoes, right in the middle of a bike section, through sand, mud, water, mud, water, you get the point. During the LEACH AR last November at John Dickson State Park, I wore my trail shoes the entire time. There were NO technical bike trails, but a lot, and I mean a lot of water, mud, whack-o-bike (is that right?), and chest high water crossings, with the bike!
I will add, the biggest problem I had, and it might be an even bigger issue with a 10 hour race, is fuel and hydration! Poor fueling & hydration is hard to recover from during a race!
Best of luck. You will have a blast!