Ran this on a hot morning earlier this summer just as a tester to gauge fitness. The mild elevation gain and super runnable trail made for a fun outing, but I was glad for the ample shade along the trail. I ended up backtracking a few times after getting lost, the large number of trails that run into the RG can make it a bit tough to follow in places. Miles 9 through 11 are the worst marked, as evidenced by a few out and backs to find the right path. Finding the right path to start can be a bit of a challenge as well, you need to bear right immediately following the sign, and come around a corner before the first G is visible.
I would not recommend stopping to refill water during the run, as the first non-pond water I saw was just before crossing Essex Turnpike, with only about two miles of the run left. However, the post-finish swim in the Eightmile River, maybe 1/2 mile backtrack along the trail, is totally worth the extra steps.