Sage is a good dude and an amazingly talented runner, but his b**** diet does not serve him well for covering lots of ground in rough terrain. I'd say he unless he changes his diet, he should stick to shorter races. You can't run 100 mile races when you fuel with chickpeas, water, and soy. His results confirm that.
Having said that, I think he'll do really well in the marathon and any sort of shorter distance run. I predict 2:21.
It's a shame that he is so married to the vegan diet.. the guy has a better engine and work ethic than most ultra runners, but the diet thing holds him back from reaching his full potential for distances above 100KM.