Wes,

Alice and I did the Huayna Picchu hike. There were some challenging spots, for sure. But there are cables to hold on too. Other places that were not quite as challenging, not so steep and narrow, there were no cables. Through those spots, our guide helped me keep my balance by having me hold onto his arm. I think you've made the right decision to do the Sun Gate hike. Ken's brother and sister-in-law, who were in our group, did it instead of Huayna Picchu, and they thought it was awesome.

P.S. You get a great view of Huayna Picchu from the Sun Gate.