St. Croix for sure! Though your missing the words wind and course roads (not terrible, just hard on the bum) in your description. Though, I have never done Savageman or Auburns Toughest Half. I did St. George Full Iron (when it was a full). It is not in the same league as St. Croix though. Rev 3 (now Challenge) Quassy is surprisingly tough. Also, had a pro friend who raced it that did plenty of other challenging courses. He comes from a mountainous region of the country. Said it was very difficult because it is very undulating. Which is true. It's constantly up, down. Not long hills, but steep enough and enough of them to wear you out. Used to train in that area frequently, while not the toughest training in the region, it is very underrated in difficulty. Those who have done it (and many times it is in the 90's) know what I am talking about. I will say St. Croix sits alone on top of all the Ironman branded ones, and all of the races I have done.

---

Running is the best source of fiber that I know of...