I had similar question about MR descent choice because the MR down was shorter but steeper than the main trail. (I am now 62 and now have a titanium knee.) I wondered if taking the longer, less steep main trail would be better for me.
Answer: Since 2006, and the 4 or 5 times that I have sufficient times recorded, I can tell you that either way takes the same for me, 6.5 hrs down either way. Many will tell you the MR down is faster, but I am glad to see both trails.
others' mileage and speeds and abilities will vary. I am hardly any faster going down than up. Best wishes
