Started just before 6am and ran the first 45min with headlamp. Temp was in the upper 30's, with a high of mid-60's. Mostly sunny. Finished just before dark. Nice day for it.
I found this trail to be a mixed bag. Lots of amazing sections, and lots of lousy ones. I like the abundance of sharp cliffs (Ragged was awesome). There are no sustained climbs/drops (except maybe Castle Craig), but a constant supply of the short and steep. Also plenty of sections so technical that they are practically un-runnable. Spent most of the day focused on good footing.
If I didn't have a watch with navigation I don't think I would have been able to stay on course to the end. I used Tom Starodaj's gpx which was spot-on. A lot of the trail is clearly marked, but in some of the busy trail network sections, and some of the trail entrances from the road sections, it was a total guessing game. I was constantly holding my watch up after guessing on a turn which helped drastically on minimizing wasted running. The turns on the roads were also not all obvious. The worst section was during miles 28-29 where I had to plow into brush taller then me under a power line, with no evidence of a trail, just following the route on my watch (I did find a post with blue paint buried in there). That section would have been impossible to follow without navigation.
The other hard part was finding water. All streams (except mile 51) were totally dry and I had to go off-trail to reservoirs as Tom did on the previous FKT. I only stopped twice for water (miles 22+41), and was battling dehydration before 2nd stop and at the end. There is also a river at 12 and a flowing stream at 51, but I passed them both up (probably not wise). Drank a total of around 5.25 liters.
I carried all the ultra-basics in my pack and around 3000 calories. Ended up consuming only around 2000 because I was so low on water.
My body held up good the whole way, and if I didn't have to deal with the low-water issues, I think I could knock off a little time. Under 12 hours is definitely possible on this, and much more likely if self-supported.