We (Chris Eveland, Matt Van Cleave) completed the Shawnee Backpack trail yesterday (January 17, 2016) in 7h 59m elapsed time. We left just before 9 am, finishing just before 5. Matt had done the north loop of the trail once before, but the south loop was new to both of us. We took only a couple of wrong turns that probably cost us at most 10-12 minutes. Other stops, including water stops, pee breaks, and Matt filtering water from a stream one point, brought our total stopping time to about 22 minutes.
The weather conditions were pretty great, despite the fact that we were getting pelted by snow from an incoming front in the last hour or so of the run. Numerous trees blocking the trail impeded us at points (although this was mostly on the north loop). Most of the trail is ATV-width and with the exception of a few muddy spots, was a soft mix of clay and gravel which is excellent for running on. The beginning and end of the south loop were single track.
Although the trail conditions were great, the route is tough: we measured approximately 8500 feet of climbing. Matt’s Suunto Ambit 3 Peak measured 8484', while Chris's iSmoothRun iPhone app measured 8547' - both from barometric sensors. (Strava, using whatever algorithm it does, changed these to 9353' for Matt and 7378' for Chris.) Most of the climbs are steep: either switchbacking up to a ridges, or following the ridge-line up and down. We only remember one gentle climb that followed a stream. The final single-track constant-grade descent to the registration area was a welcome reward for a hard day's adventure.
Matt had talked briefly with Michael Owen briefly on Strava about the current FKT and about attempting one soon. As far as we know, our time is the FKT, although we have no doubt that Michael Owen will destroy it pretty much whenever he wants to. 
Links:
- Chris's iSmoothRun Data
- Matt's Ambit Data
- Chris's and Matt's Strava Activities.