I finished a week of fastpacking including nearly all of the Hardrock 100 course and then 70 miles on the Colorado Trail into Durango. I had rain every day ranging from 15 minutes to 7 hours. These were major afternoon storms that lasted into the evening. On the last night there was a 4 hour lightening and thunderstorm that kept me awake until 2am.
The course is tough with 33,000' of gain (nearly 2x WS100). It follows trails as clear as major dirt roads to as minor as a line of course markers through the willows. It averages 11,200' of elevation and only drops below 10,000' four times. There are three somewhat technical cross country passes and the course ascends to the top of Handies Peak at 14,048'.
Most of your time is spent above timberline and aid stations can be 8-9 miles apart (and on the tougher sections this could be 3-4 hours). You'll have wet feet much of the time--especially if it rains but multiple stream crossings, mud and snow sections and wet flowers/plants will keep them wet even if it's clear. The wildflowers are outstanding.
Fastpacking the course (little running) took 48 hours of moving time over 3.5 days. I lost a pound per day as I only ate 4000 calories daily and burned 7500. I started at 3pm Saturday, August 2 and covered only 11 miles/5000' gain before dark (8:45pm). The next two days were better: I was able to cover around 30 miles and 8000' of gain (not including catching a 1mile then 3 mile ride on two fairly dull road sections) each day. I hiked from 6:15am to around 8pm each day. I stopped for a 15-30 minute breakfast, but just kept hiking through lunch as the weather generally wasn't conducive to stopping. The final day was the toughest. Bad weather, difficult passes, route finding challenges and unrelenting climb/descend cycles had me cover only 22 miles but 10,000' of gain! Clearly the last 25 miles in the CCW direction or first 25 in the CW direction are the toughest. If I chose I'd want to do the race in the CW direction (it changes direction each year).
The trip into Durango on the Colorado Trail was much more tame. I averaged 31 miles per day but had only around 4000' of gain each day. The trail was fairly well defined and marked.